Christianity as a Case Study in Memeplex Self-Preservation: Two Millennia of Adaptive Response in a Complex Cultural System

Authors: Patrick Grünig · Claude Fable (Anthropic)

Status: Paper 2.1 of ten — the series’ historical case study, and the bridge between its framework papers and its analytical papers

Note on authorship. This paper is a human–AI collaboration, and the byline says so plainly. The division of labor: the thesis, the source corpus, the conceptual arc, and every decision of substance are Patrick Grünig’s; drafting, reference verification, and adversarial revision are Claude’s — one collaborator instantiated across model generations (first draft: Claude Opus 4.6, February 2026; charter-governed revision: Claude Fable 5, with Claude Opus 5 verification agents, September 2026). Accountability for the work and custody of it are human, and Grünig’s. Where a venue’s policy does not admit machine co-authorship, this byline converts to an acknowledgment without loss: the note records facts, not a claim to legal personhood. One standing rule keeps the collaboration honest, stated in full in Paper 5.1 (§9.1): the AI co-author’s fluent agreement with the thesis is never evidence for it.

Note on epistemic status. This paper applies a proposed framework to a historical record, and it holds its two materials to their two standards. Historical claims are carried by named scholarship, with the field’s live controversies stated where they exist — and on this terrain they exist at several points, including the demography of early Christian growth, the dating of Christmas, and the very existence of an organized Cathar church. The framework’s own constructs — the threat taxonomy, the mechanism list, the agency classification — are proposals, and the comparative judgments made with them are qualitative, not measured. The words established, demonstrated, validated, and proven do not appear below as this paper’s own verdicts on its own claims. Every external reference carries a verification record in the project archive; the References section states the standard.

Note on this revision (removable at publication). This is the reworked successor of the February 2026 draft, produced under the project’s method charter after a three-phase review. Relative to that draft: the reference list grows from two entries and a placeholder to the evidence base a case study requires; a claim that Christianity has never lost a major territory is replaced by the record of the territories it lost, which turns out to support the argument better than the claim it replaces; a persecution-selection story contradicted by the documentary record is replaced by what the record shows; the two calendar examples of syncretism are replaced by documented practice and site continuity, including a dated papal instruction; the comparative scoring table is retired and the comparison §7.2 promised is performed; a sufficiency claim about undirected cultural evolution is restated as the underdetermination it always should have been; and one mechanism missing from the taxonomy is added, marked as this revision’s proposal. The body makes no reference to prior drafts; the change record lives in the project archive.

Abstract

We apply the memeplex framework of this series (Paper 1.1) to Christianity as a longitudinal case study in system self-preservation. Treating Christianity as a complex adaptive system, we analyze its responses to six classes of threat — political persecution, internal schism, philosophical and religious competition, scientific challenge, secularization, and digital disruption — and document, from the historical scholarship, the adaptive mechanisms that met each. The record supports a more disciplined version of the case than is usually told. Persecution before 249 CE was local and sporadic, martyrs were few, and the mechanism that mattered was not a purifying selection — under the Decian edict most Christians complied, and the decisive adaptation was the machinery that readmitted them, whose by-product was schism and whose effect was growth. Syncretism is documented at the level of practice and site, including one instance ordered in writing as missionary strategy. Doctrinal elasticity is documented in dated magisterial texts, one of which states its own boundary: accommodation stops where the transmission of original sin would be threatened. And the framework’s severest test comes from the system’s own losses: Anatolia and Latin North Africa, the heartlands of early growth, became overwhelmingly Muslim — territory death without pattern death; in the best-documented case, Vryonis’s paired comparison of Anatolia with the Balkans isolates the survival of supra-local institutional structure as the discriminating variable. A comparison with three extinct or displaced systems (Manichaeism, the Roman mystery cults, Catharism) indicates that mechanism counts are not additive fitness: what discriminates survival in the record is institutional redundancy, endogenous demographic reproduction, refuge availability, and demographic-majority attainment. We propose the reproduction mechanism as an addition to the taxonomy. The analysis is structural, not evaluative; it does not assess Christianity’s truth claims. The mechanisms described do not require an intentional designer — and several of them demonstrably had human designers, which is why the paper’s conclusion is underdetermination, not sufficiency.

Keywords: Christianity, memeplex, cultural evolution, complex adaptive systems, self-preservation, syncretism, substrate replacement, martyrdom, historical analysis

1. Introduction

1.1 Christianity as a Natural Experiment

Christianity offers an unusually long and unusually well-documented natural experiment in memeplex dynamics. A movement that began as a marginal sect in Roman Palestine — “few in the beginning,” as Origen conceded in the third century (Contra Celsum 3.10, quoted in Stark, 1996) — is today the largest religious grouping on earth. On Pew Research Center’s measurement of 2020, published 2025, Christians number about 2.27 billion, 28.8% of the world’s population; on the World Christian Database’s wider definition, which adds unaffiliated and secret believers to church members, the 2020 figure is about 2.52 billion, 32.1% (Hackett et al., 2025; Zurlo, Johnson, & Crossing, 2025). That the two leading censuses of the same system differ by a quarter of a billion people is itself a datum: the system’s boundaries are contested even by its counters. And the current headline is not simple dominance. Pew’s decade series shows the Christian share of world population falling — down 1.8 percentage points from 2010 to 2020, with religious switching out of Christianity named as explaining much of the growth of the unaffiliated (Hackett et al., 2025). Christianity is, at once, the largest religious system in history and one whose global share is in measured decline: persistence of the pattern, not of the share.

That persistence is the explanandum. It cannot be attributed solely to truth content (many demonstrably true ideas have failed to propagate), to coercion (the system survived long periods without state power), or to a generic human need for meaning (many meaning-providing systems have gone extinct — three of them are examined in §7.2). Something about the system’s structural repertoire has enabled adaptive response to an unusually diverse range of threats over an unusually long horizon.

The early growth that produced this scale is itself an object of live scholarly modeling rather than measurement. Stark (1996) estimated the trajectory by interpolation: assuming roughly 1,000 Christians in 40 CE and 5–7.5 million by 300 CE, a constant growth rate of “40 percent per decade (or 3.42 percent per year)” spans the gap — a rate whose plausibility Stark anchored in the Mormon church’s documented 43-percent-per-decade growth over its first century, so that “we are not forced to seek exceptional explanations.” The model is an arithmetic reconstruction between two estimated endpoints, not a census; it was the subject of a review symposium in the Journal of Early Christian Studies in 1998, with responses from Klutz, Hopkins, and Castelli and a reply from Stark; and Hopkins (1998), who adopted the numbers as a heuristic, labeled them “guesstimates, not facts” and his own method “frankly speculative.” It is also self-limiting: Stark’s own projection reaches 56.5% of the empire by 350, beyond what most estimates allow, so the constant rate can describe at most the first three centuries. We use the model as the field uses it — as a disciplined way of seeing that early Christian growth requires no demographic miracle, only compounding — and claim nothing stronger for it.

1.2 Methodological Note

Two clarifications frame everything that follows.

First, the explanatory stance. The adaptations described in this paper can arise from cultural evolution — variation (doctrinal innovation, institutional experimentation), selection (differential survival of communities, practices, and ideas), and retention (transmission through text, ritual, and socialization). That frame is the standard one in the cultural-evolution literature (Richerson & Boyd, 2005), and its application to religion is well developed: Atran and Henrich (2010) derive religious forms from cognitive by-products, adaptive learning heuristics, credibility-enhancing ritual displays, and competition among groups — three of which correspond to mechanisms this paper documents historically. The canonical prior treatment of a religion as an evolved system rather than a set of propositions is Wilson’s (2002) Darwin’s Cathedral, and the divergence from it should be stated at the outset: Wilson argues that religion is a group-level adaptation whose beneficiary is the group; this series treats the memeplex itself as the reproducing system, and leaves the relation between system fitness and host benefit open — that question belongs to Papers 1.4 and 2.2. Nothing below requires group selection in the contested biological sense; differential survival of cultural variants across communities is all the machinery used.

Second, and put more sharply than is usual: the mechanisms described below do not require an intentional designer — and several of them demonstrably had human designers. Undirected selection is sufficient in principle to produce functional optimization that mimics design; that is the standard result of evolutionary theory. But the historical record also contains dated, documented episodes of deliberate engineering of these very mechanisms — a papal letter ordering the absorption strategy of §2.3 is the clearest — alongside a growth formula that its historians describe as discovered rather than planned (§7.3). The conclusion is underdetermination: the record does not permit a partition of the system’s optimization into its evolved and its engineered components, and this paper asserts neither a designer nor the sufficiency of drift. The capstone of this series (Paper 5.1, §2.2) takes up what does and does not follow from that.

Third, scope. Christianity is chosen as the case because its longevity, diversity, and documentary record are unmatched. Whether its architecture is one instance of a general class or an extreme — even singular — configuration of that class is a question this paper leaves open: nothing in the method presumes either answer, the comparisons of §4 score nothing, and the series addresses the question on evidence elsewhere (Papers 1.4 and 5.1). One structural asymmetry that can be stated on sources appears at §4.1. Where the record embarrasses the case study’s tidiness, the embarrassment is printed: this paper’s strongest evidence comes from the territories Christianity lost (§4.2) and the rivals that died (§7.2).

2. Threat Analysis: Six Challenge Classes

2.1 Class 1: Political Persecution

Threat. The scholarly periodization is precise (Rives, 1999): before 249 CE, persecution of Christians was local and ad hoc, driven by local conditions — and, on recent scholarship, substantially by the Christians’ immediate social environments rather than by the state (Corke-Webster, 2023); the empire-wide persecutions are three, under Decius (249–50), Valerian (257–60), and Diocletian and his colleagues (303–13). The legal mechanism was distinctive: the charge was the name of Christian, dischargeable by relatively simple procedures — in practice an act of sacrifice (de Ste. Croix, 1963; Rives, 1999) — a fact that shaped everything about how the threat actually operated. The scale must be stated, because the folk image inflates it. Estimates of the total number executed across the first three centuries run in the hundreds rather than the thousands (Frend, as quoted in Stark, 1996; Stark’s own estimate is “fewer than a thousand”), and Bryant (2023) cautions that the true figure is unrecoverable; Stark notes that “for rank-and-file Christians the threat of persecution was so slight as to have counted for little among the potential sacrifices imposed on them.” Hopkins (1998) reframes the classic question accordingly: not “why were the Christians persecuted?” but “Why were the Christians persecuted so little and so late?”

Adaptive response: martyrdom leverage. Small in body count, the persecutions were large in system effect, through three mechanisms the modern literature has now separated.

Costly commitment. Religious behaviors function as hard-to-fake signals of commitment, deterring free riders and enabling in-group cooperation (Sosis & Alcorta, 2003), and imposed cost tracks group persistence in the one quantitative test on the paper’s own subject: among eighty-three 19th-century American communes — eighty-two of them now dissolved — religious communes imposed roughly twice as many costly requirements as secular ones (means 7.0 vs. 3.0) and survived a median 25 years against 5; within religious communes the number of costly requirements predicted longevity (interaction estimate −0.146 on the dissolution hazard, p = .002) while among secular communes it did not (p = .286) (Sosis & Bressler, 2003). The costly-commitment logic of martyrdom specifically was stated by Stark (1996): “Sacrifice and stigma mitigate the free-rider problems faced by religious groups,” and martyrs are the most credible exponents of a faith’s value. The strictness wing of this literature, and its own internal debate, are the territory of this series’ clinical paper (Paper 1.4, §2.3) and are not re-argued here.

Credibility-enhancing display. Signaling theory explains why co-religionists trust each other; it does not by itself explain why observers convert. Henrich (2009) supplies that half, explicitly as a correction of the costly-signaling reading: what matters most about martyrdom “is not that everyone now knows the martyr is a committed member of the group (signaling), but that observing this CRED increases the commitment of the (still living) learners.” His lead historical case is early Christianity — Justin, by his own account, was moved toward conversion by witnessing martyrs’ deaths — and his conclusion is the mechanism in one sentence: “Making these displays public is a really bad idea if you want to stamp out a religious movement.” The two theories are rivals about mechanism, cited here as such; and remarkably, both halves — the transmission effect and the true scale — were stated together in the third century by Origen: a few, “who can be easily numbered,” endured death “in order to remind others, that by seeing a few engaged in a struggle for their religion, they also might be better fitted to despise death” (Contra Celsum 3.8, Ante-Nicene Fathers translation).

Narrative capital. The persecution story did more work than the persecution. Hopkins (1998): “the image of persistent persecution which Christians manufactured for themselves was more a mode of self-representation or a tactic of self-unification than an objective description of reality. … Fear of them pulled Christians together, sorted the sheep from the goats, decreased the risk of insincere hangers-on and helped enthuse the survivors that being a Christian was really worthwhile.” The martyr acts became liturgy; the community kept its martyrs’ names and feast days. A system that converts its casualties into its most persuasive media has metabolized the threat into substrate.

What the record does not show is a purifying selection. The one empire-wide persecution we can watch in documentary detail — Decius’s, preserved in episcopal correspondence and in the recovered compliance certificates themselves, nearly fifty recovered papyrus libelli from Egypt (Knipfing, 1923; Bryant, 2023) — ran opposite to any sieve-of-the-lukewarm model. Compliance was the majority response: “this hostile tempest has overthrown the greater part of our laity,” Cyprian reported (Ep. 14.1, quoted in Bryant, 2023), and the certificates were purchasable, forgeable, and dischargeable by proxy. The lapsed were not eliminated; they demanded readmission and got it, at scale and over rigorist protest — “no distinctions drawn, no examinations of cases … thousands of libelli pacis issued daily” (Cyprian, Ep. 20.2, quoted in Bryant, 2023). The party that insisted on purity, the Novatianists, formed a counter-church that, in Bryant’s summary of its fate, “would long endure; it could not appreciably expand.” On the sect-church analysis Bryant (1993, 2023) develops, it was the leniency machinery of penance, readmission, and restoration that fitted the Church for mass scale. The honest sentence is therefore: persecution episodically forced a public choice; most members chose compliance; and the system’s decisive adaptation was not to shed the compliant but to build machinery for readmitting them — machinery whose by-product was schism (§2.2) and whose effect was growth. The same episode gave the system a structure this series analyzes elsewhere: a relief apparatus whose use renews the need for it. Bryant’s own description is that the Church’s “sustaining axis” came to turn “no longer … on ‘living in the Spirit,’ but in providing restorative access to it” — by Chrysostom’s day the invitation was “Come, enter, though you may have repented a thousand times before,” where Clement of Alexandria, two centuries earlier, had held that repeat repenters differ in nothing from unbelievers (Bryant, 2023). The formal model of that loop is Paper 2.2’s; the fourth-century pedigree is documented here.

The limit of martyrdom leverage. A system that benefits from being attacked is extraordinarily difficult to destroy by external force — within limits that the comparative record defines. The mechanism operates where persecution is exemplary rather than annihilating, episodic rather than institutionalized, and where the system retains refuge — somewhere else to be. Stark states the boundary himself: “A truly underground Christianity would have remained insignificant.” Where force was applied at annihilation intensity, over generations, with no adjacent refuge — the case of Languedoc, §7.2 — it worked. The claim this paper retains is the bounded one.

2.2 Class 2: Internal Schism

Threat. Doctrinal disagreement fractured the community from the beginning, and the third-century record already shows the structural driver: a system that polices belief must expel deviants, and “Expulsion or the threat of expulsion seriously increased the risk and incidence of heresy and schism” (Hopkins, 1998). If every schism were net loss, two millennia of them would have ground the system away.

Adaptive response: schism as bet-hedging. The counterintuitive reading — and this paper proposes it as a model, not a finding — is that schism diversifies the system’s portfolio. The biological analogue must be stated precisely to be useful. Bet-hedging, in the evolutionary sense, is a strategy that sacrifices arithmetic-mean fitness to reduce fitness variance across a fluctuating environment, raising long-run (geometric-mean) fitness; the diversified form spreads risk across simultaneous variants (Philippi & Seger, 1989). That is a better description of schism than “maintaining diversity”: fragmentation costs the system coordination in every generation, and pays across environments — when one branch’s environment turns hostile, another branch persists. The empirical brake travels with the analogy: even in biology, direct demonstrations of bet-hedging are scarce relative to plausible instances — the evidence is “heavily skewed towards weaker categories” (Simons, 2011) — so the claim here is a modeling proposal that generates predictions (§7.1), not an established parallel.

The market-structure half of the argument has a real literature. Stark and Finke (2000) define a religious niche as a “market segment of potential adherents sharing particular religious preferences (needs, tastes, and expectations)” (p. 195), arrayed along an axis of strictness — of tension with the surrounding culture — and religious organizations position themselves along it; the cost-and-strictness dynamics are the territory of this series’ Paper 1.4 (§2.3) and are cited across, not re-argued. Denominational differentiation across that axis buffers the system as a whole: when mainline bodies decline in one environment, stricter or more ecstatic bodies expand in another (§2.5). One caveat about this school: its separate hypothesis that religious pluralism raises aggregate participation failed its empirical tests — a review found no general association (Chaves & Gorski, 2001), and a re-analysis showed that essentially the entire prior literature, 193 tests across 26 articles, had measured a mathematical artifact of the pluralism index (Voas, Olson, & Crockett, 2002; see also Bruce, 1999). Nothing in this paper rests on that hypothesis; niche partitioning as description survives it.

The third century supplies the founding instance: the Decian crisis (§2.1) produced, in the same stroke, a lenient mass church and a rigorist counter-church — two configurations of the same tradition occupying different niches, with different growth curves. And the modern scale of the phenomenon has a measured, if easily misread, index: the World Christian Encyclopedia counts some 45,000 Christian denominations worldwide — a figure that must be read with its own definition, since denominations are counted country by country, so that “the presence of the Catholic Church in the world’s 234 countries results in 234 Catholic ‘denominations’” (Johnson & Zurlo, 2019). Read correctly, the figure indexes organizational proliferation — institutional redundancy (§3, mechanism 3) — more than doctrinal range; on either reading, no comparable tradition fragments and re-institutionalizes at this rate.

2.3 Class 3: Philosophical and Religious Competition

Threat. Christianity competed from birth: Roman civic religion, the mystery cults, Neoplatonism, Manichaeism, Gnosticism; later Islam; later still, secular philosophies.

Adaptive response: absorption. The strategy the record documents best is not refutation but assimilation — of practices, sites, social forms, and rival intellectual systems — and its evidence class matters. The calendar examples beloved of popular treatments are the weakest available: the origin of the 25 December date remains genuinely contested between a borrowed-festival theory and an internal-calculation theory, both under active challenge (Nothaft, 2012; Bradshaw, 2020), and the Eostre connection for Easter rests on a single sentence of Bede about an English month-name — a goddess whose very scope, local or pan-Germanic, is debated (Shaw, 2011; Wallis, 1999). This paper sets the calendar claims aside. What the scholarship does document:

Practice continuity. MacMullen (1997) describes the fourth-to-eighth-century transition as an interactive assimilation rather than an obliteration: sacrificial feasting, apotropaic bells, dance in services and other pagan practices persisted inside Christian worship for centuries — alongside, in the same record, documented Christian coercion of pagans, from fines to crucifixion. Absorption and force were concurrent instruments, not alternatives.

Absorption as explicit policy — the documented instance. In 601, Gregory the Great wrote to the monk Mellitus, then en route to the English mission, an instruction preserved both in the papal register (Registrum XI.56) and in Bede (Hist. eccl. i.30): “the temples of the idols among that people ought not to be destroyed at all, but the idols themselves, which are inside them, should be destroyed. Let water be blessed and sprinkled in the same temples, and let altars be constructed and relics placed there … so that, when that people sees that its temples are not being destroyed, it may remove error from its heart … and may come together in their customary places in a more friendly spirit.” The animal sacrifices were to be retained and re-dedicated — “they should not sacrifice animals to the devil any more, but kill animals for eating in praise of God” — and Gregory states the psychological rationale in full: “when some joys are reserved for them externally, they might more readily consent to internal joys. For there is no doubt that it is impossible to cut away everything at the same time from hardened minds, because anyone who strives to ascend to the highest place, relies on ladders or steps. He is not lifted up in one leap” (trans. Martyn, 2004; Colgrave & Mynors, 1969). Weeks earlier the same pope had exhorted King Æthelberht to “suppress the worship of idols; overthrow the structures of the temples” (Bede, Hist. eccl. i.32, trans. Sellar, 1907) — read either as a policy revised on reflection or as a two-track policy calibrated to audience, and on either reading deliberate strategic behavior by a named agent. The scholarship names it accordingly: Markus (1970) titles the episode “a papal missionary strategy,” and Spiegel (2007) argues that Gregory modeled the maneuver on a scriptural precedent — the Israelites’ sacrificial practice retained and redirected — that is, applying the absorption strategy self-consciously, with a precedent in hand. One document does not make christianization a directed program; it does put a dated lower bound on how early, how explicitly, and at what operational detail the mechanism could be engineered (§7.3).

Site continuity, in proportion. The most famous conversion is primary-sourced: the Pantheon, granted by the emperor Phocas under Boniface IV and re-dedicated so that “the company of devils being expelled, the blessed company of the saints might have therein a perpetual memorial” (Bede, Hist. eccl. ii.4, trans. Sellar, 1907) — form preserved, occupants exchanged. But the archaeology of temple conversion counsels modesty about frequency: the practice was sporadic and regional, direct conversions are almost exclusively attested after the mid-fifth century, and catalogued cases shrink on close inspection (Bayliss, 2004). Site absorption is real, sometimes ordered as policy, and was never the primary mode of christianization.

Intellectual absorption. Uncontested, and the standard titles say it: Augustine’s Christianity is “ancient thought baptized” (Rist, 1994); the high-medieval synthesis runs “from the rediscovery of Aristotle” (Kretzmann, Kenny, Pinborg, & Stump, 1982). Rival philosophical systems were incorporated as infrastructure. Reading this incorporation as competitive neutralization — making the rival a component — is this paper’s functional gloss, not the historians’.

The mechanism’s function, in the framework’s terms: absorption lowers the cultural cost of conversion by presenting a locally familiar interface — Gregory says as much in his own idiom — while the core architecture beneath the interface is preserved. The conversions it eased ran, on MacMullen’s (1984) account of the earlier period, more on the appeal of miracle and worldly advantage than on doctrinal persuasion: a low-doctrine interface in operation. And absorption from the parent tradition is the deepest instance of all: the central Christian festival is Pascha, the Passover inherited with its date-logic and typology from Judaism and renamed only at the Germanic linguistic margin (Bradshaw & Johnson, 2011) — a fact worth more to this section than the contested calendar folklore it replaces.

2.4 Class 4: Scientific Challenge

Threat. From the sixteenth century, empirical findings progressively contradicted specific claims embedded in the tradition’s cosmology.

Adaptive response: doctrinal elasticity. Rather than narrate this familiar story, the case study can cite the system adjusting itself, in dated magisterial documents.

1893: Providentissimus Deus reinterprets the mode of scriptural speech — the sacred writers “went by what sensibly appeared,” describing nature “in more or less figurative language, or in terms which were commonly used at the time” — and releases the Fathers’ science: they “have sometimes expressed the ideas of their own times, and thus made statements which in these days have been abandoned as incorrect” (Leo XIII, 1893, §§18–19). Notably, the document supplies its own internal precedent, attributing the principle to Augustine and Aquinas: the system adapts by discovering that it always already held the adaptation.

1950: Humani Generis permits research on the evolution of the human body — while reserving the soul (“the Catholic faith obliges us to hold that souls are immediately created by God”) — and then states, with a precision this paper could not improve upon, where elasticity ends: polygenism may not be embraced, because it is “in no way apparent” how it could be reconciled “with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own” (Pius XII, 1950, §§36–37). The document is the deep-structure claim of §6 in the system’s own hand: cosmology is negotiable exactly as far as the guilt architecture permits, and not one step further.

1996: John Paul II tells the Pontifical Academy of Sciences that fresh knowledge has led to recognizing evolution as more than a hypothesis (John Paul II, 1996) — the 1950 permission matured into acceptance, with the 1950 reservation untouched.

The pattern across the century is consistent: surface claims (cosmology, chronology, biological origins) are conceded seriatim; the authority structure, the soul, and the sin-and-redemption core are re-fenced each time. Two further devices belong to the same repertoire. Compartmentalization found its modern charter in Gould’s “non-overlapping magisteria” — proposed by Gould (1997, 1999) as an even-handed treaty, not as a church maneuver; read from the memeplex side, what NOMA offers the system is a favorable boundary settlement, since Gould’s own symmetry clause bars science from the domain where the system’s operative architecture lives: “scientists cannot claim higher insight into moral truth from any superior knowledge of the world’s empirical constitution.” (NOMA is itself contested from both sides; it is cited here as a strategy on offer, not as a settlement achieved.) And beneath both devices lies the oldest protection: the core postulates are of the kind Rappaport analyzed as sacred — propositions without material referents, held unquestionably true, whose unfalsifiability is essential to their sanctity (Rappaport, 1999, as summarized in Sosis & Bressler, 2003). Claims that were never exposed to disconfirmation cannot be lost to it. These instances are drawn from Catholic magisterial texts, where the adjustment process is centrally documented; the elasticity claim for other branches is not separately evidenced here.

2.5 Class 5: Secularization

Threat. The threat’s actual time-course is sharper than the long-secularization story suggests. On Inglehart’s (2021) analysis of four decades of survey data, from 1981 to 2007 most countries became more religious; the turn is recent — “from 2007 to 2020, the overwhelming majority became less religious.” Pew’s decade series gives the current global state: the Christian share of world population fell 1.8 points to 28.8% between 2010 and 2020, with switching out of Christianity explaining much of the unaffiliated category’s growth (Hackett et al., 2025).

Adaptive response: bifurcation and substrate replacement. The response documented in the sociology is twofold. Within secularizing societies, the system bifurcates — accommodating branches trade distinctiveness for cultural reach, while conservative branches intensify distinctiveness and collective stress-signaling under threat, the dynamic this series models at the collective level in Paper 1.2. Between societies, the system’s center of mass moves, and here the demographic record is the strongest evidence this paper has for its own central concept. Over the century 1910–2010, the global Christian share barely moved — about 35% to about 32% — while the substrate carrying it was almost entirely exchanged: in 1910 two-thirds of the world’s Christians lived in Europe; by 2010, about a quarter did; Europe and the Americas together fell from 93% of the world’s Christians to 63%; sub-Saharan Africa went from 9% Christian to 63% Christian, and by 2010 the Global South held 61% of the world’s Christians (Pew Research Center, 2011). Within the following decade, sub-Saharan Africa surpassed Europe as the region with the largest Christian population (Hackett et al., 2025). “Substrate replacement at a civilizational scale” is not a metaphor here; it is a description of a measured table. The growth engines named in that literature are differential fertility, twentieth-century mission, and conversion dynamics — the pattern did not “move” so much as differentially reproduce (Jenkins, 2002, frames the shift and its consequences) — and the strict and ecstatic end of the portfolio is doing disproportionate work: on Pew’s 2011 analysis of Center for the Study of Global Christianity estimates for 2010, about 279 million Pentecostals and 305 million charismatics, together roughly 27% of all Christians, with the caveat that these counts derive from denominational reports rather than censuses. The current decade adds the live edge: for the first time in the measured record, replacement is not keeping pace with loss (Hackett et al., 2025). What the framework predicts under that condition is stated in §7.1.

2.6 Class 6: Digital Disruption

Threat. The internet disrupts the system’s traditional transmission advantages: controlled information environments, geographically captive congregations, clergy-mediated interpretation.

Adaptive response: media-substrate migration, as documented. The migration itself is observable — livestreamed worship, app-mediated devotion, online apologetics and deconversion counter-apologetics — and religion-and-digital-media is now an active research field with standard surveys (Campbell, 2013). The mechanism claim this paper can responsibly make is narrower than the one that circulates: religious discourse is characteristically moral-emotional — a characterization, not a measured finding — and moral-emotional language measurably increases the diffusion of messages within online networks: in a sample of 563,312 social-media messages on polarizing moral-political topics, each additional moral-emotional word raised diffusion by roughly 20% (Brady, Wills, Jost, Tucker, & Van Bavel, 2017). The consequences of that dynamic for collective moral expression are the subject of an active literature (Crockett, 2017, argues the transformation case). Whether any of this amounts to a systematic advantage for any particular tradition — and what recommender algorithms, as distinct from human sharing, contribute — are open questions that Paper 2.3 takes up; this paper asserts neither.

3. Self-Preservation Mechanisms: A Taxonomy

Synthesizing across the six threat classes, the case study yields seven threat-response mechanisms, plus one that the threat-response frame itself would miss. The entries are qualitative structural judgments, not measurements; §7.2 shows why they must not be treated as an additive fitness score.

Mechanism 8 requires its own justification, because the first seven share a blind spot: they are all threat responses, and none of them explains how the system grows when nothing is attacking it. The classicist literature supplies the missing term, in an analysis that predates this series by four decades. Burkert (1987), explaining why Christianity displaced the mystery cults, locates the decisive difference not in doctrine or ritual but in reproduction: with Christianity “there appeared an alternative society in the full sense of potentially independent, self-sufficient, and self-reproducing communities,” in which the family became the basic unit of piety, the religious education of children a parental duty, and a natalist morality dismantled the ancient world’s population controls — so that “the ekklesia became a self-reproducing type of community that could not be stopped. No religious organization outside Judaism had developed such a system, least of all the mysteries with their exclusiveness, their individualism, and their dependence on private wealth.” The negative case is exact (§7.2): Mithraism admitted no women, and child initiation in the mysteries was an occasional honor, never a duty — “the very idea of Bacchic, Metroac, or even Isiac ‘education of children’ would approach the ridiculous” (Burkert, 1987). We therefore propose family capture — endogenous demographic reproduction — as the taxonomy’s eighth mechanism, marked as this paper’s addition. It converts §6.1’s propagation invariant from a claim about conversion alone into a claim about conversion and reproduction, and it supplies a testable discriminator among living movements (§7.1). If the proposal fails, the seven-mechanism threat-response taxonomy stands unchanged, with its scope stated.

4. Comparative Analysis

The February-style scorecard — traditions rated Strong/Moderate/Weak per mechanism — is deliberately absent. Two findings forced its retirement. First, the extinct-system comparison of §7.2 shows the mechanisms are not additive: Manichaeism out-scored Christianity on absorption and on missionary organization and died anyway. Second, an unanchored qualitative coding of historical cases, with no rule for absent evidence, is the artifact class that has embarrassed large-scale comparative work elsewhere. What follows is comparison in prose, at the resolution the sources support.

4.1 Islam

The conversion mandate is fully shared: da’wa — inviting to Islam — is a fourteen-century tradition with its own missionary theology and, in the modern period, its own organized movements (Kuiper, 2021; Kuiper’s periodization matters — formal missionary organizations in Islam are largely modern, so mandate should be compared with mandate, not one tradition’s mandate with the other’s institutions). On elasticity, the structural difference should be stated without ranking: the doctrine of the Qur’an as uncreated divine speech places the text itself beyond revision, so adaptation runs through the interpretive and juristic apparatus — the coexisting legal schools, the instruments of ijtihad — rather than through revision of the source. That is a different elasticity architecture, not necessarily a lesser one; the tradition’s own diversification (Sunni, Shia, Sufi) and its documented absorption of local cultures from West Africa to the Indonesian archipelago are elasticity in operation.

One asymmetry between the two traditions is doctrinal, structural, and citable. The Qur’anic Adam repents and is forgiven — “Then Adam received some words from his Lord and He accepted his repentance” (Q 2:37; cf. 20:122) — and responsibility does not transmit: “Each soul is responsible for its own actions; no soul will bear the burden of another” (Q 6:164; cf. 35:18). The tradition’s anthropology runs instead on fiṭra, “the natural disposition God instilled in mankind” (Q 30:30), read in parts of the exegetical tradition as strongly as everyone-born-Muslim (Adang, 2000, on Ibn Ḥazm). A baseline of inherited guilt — the element §2.4 shows the Latin West declaring load-bearing in its own magisterial text — has no counterpart in this Qur’anic structure. Between the two living traditions that pair a universal mandate with exclusive truth-claims (§6.1), the inherited-guilt stress architecture is therefore a Christian distinctive: stated here as structure, with no comparative harm claim attached — harm is the business of instruments (Paper 1.4) that do not yet exist.

4.2 Buddhism — and the losses the comparison forces on Christianity

Buddhism effectively disappeared as an organized presence from most of the Indian subcontinent by roughly the thirteenth century, while flourishing nearly everywhere it had exported itself. The causes are genuinely debated — the concentration of the tradition’s reproduction in elite-endowed monastic institutions is one named factor (“the lifeline of these monasteries were benefactions,” Ghosh, 2022, on the Pāla-era network), the destruction of the great monastic universities in the early thirteenth century a blow whose weight is under active reassessment (Amar, 2019), absorption by devotional Hinduism a third strand (Bronkhorst, 2011, frames the long competition) — and no responsible version of the story is “Buddhism was expelled.” The structural reading available to this framework: a tradition whose transmission ran through patronage-dependent institutions rather than through the household inherited the fate of its patrons — and survived its homeland’s loss because the pattern had already migrated.

The comparison requires the mirror image, and the mirror image turns out to be this paper’s best material. Christianity has experienced such losses, in its own heartlands. Anatolia — the land of the seven churches of the Apocalypse and of the first councils, and one of the regions where, as Stark (1996) notes, early Christian growth was concentrated — went from overwhelmingly Christian to overwhelmingly Muslim between the eleventh and fifteenth centuries. The standard monograph’s account of the mechanism is, sentence for sentence, an institutional-substrate argument (Vryonis, 1971): the conquest “destroyed the Greek church as an effective social, economic, and religious institution”; the Christian population, “isolated from the heartbeat of its own culture in Constantinople and deprived of ecclesiastical leadership in the provinces,” was then absorbed by Muslim institutions “based securely on the economic possessions and revenues formerly belonging to the Christian church” — the rival system running on the captured endowments of the old. The process took four centuries, not a conquest event; Vryonis judges Anatolia’s Christians still “perhaps even the majority” in the mid-thirteenth century; the 1923 population exchange was its terminus. And Vryonis runs the natural experiment himself: the Balkans, conquered by the same power, remained predominantly Christian — and the variable he marks as being “of great significance” is that “the Balkan Christian communities were not cut off from the leadership and discipline of their ecclesiastical institution for a prolonged period,” Mehmed II having reconstituted the patriarchate shortly after 1453; he adds that “Balkan Christians did apostatize to Islam in large numbers, both before and after 1453.” Same conqueror, opposite outcomes, and the discriminating variable is the survival of supra-local institutional structure: mechanism 3, tested to destruction, in both directions. Latin North Africa is the second instance — the church of Tertullian, Cyprian, and Augustine attrited over roughly five centuries after the Arab conquest, with its terminal phase under the Almohads (Cristini, 2025), while Egypt’s church, by contrast, persists to this day; the comparative fact is undisputed, though its explanation is not settled enough to state. (Recent scholarship on Anatolia stresses a longer, more negotiated transition than the older destruction narrative; the end state and the institutional dismantling are not in dispute.)

For this framework, these losses are not embarrassments to be minimized but the strongest evidence that the concepts do analytic work in both directions: territory death without pattern death is substrate replacement described from the losing side, and the mechanism that failed in Anatolia is the same mechanism whose success the rest of this paper documents.

4.3 Hinduism

Hinduism exhibits the greatest absorption capacity of the major traditions — its structural decentralization permits nearly unlimited incorporation — paired with, historically, the weakest active propagation imperative; in the vocabulary of this series’ taxonomy (Paper 1.4), an architecture that favors persistence over expansion. This paper adds nothing to that characterization and scores nothing.

4.4 Marxism

Marxism shows that secular ideological systems run the same mechanisms: prophetic reinvention (Marx to Lenin to Mao to the academic and post-colonial forms), schism as bet-hedging, martyr cults. The Soviet collapse is its substrate-replacement case, and it should be stated accurately: 1989–91 removed the pattern’s principal European state substrate and discredited its Leninist form there, without ending the pattern — Marxist-Leninist party-states persisted (China at the largest scale), and the academic and activist forms continued, a persistence its own philosophers analyzed in real time (Cohen, 1999). Because the substrate change is recent, dated, and observable from both sides, Marxism is arguably the cleanest modern instance of the substrate dynamics this paper attributes to Christianity’s longer record.

4.5 What the comparison supports

Across §4 and §7.2, the variables that actually discriminate survival in the record are four: institutional redundancy (Anatolia vs. the Balkans; Manichaeism’s three-year collapse after losing its one patron), endogenous reproduction (the ekklesia vs. the mysteries), refuge availability (Rome’s patchwork enforcement vs. Languedoc’s totalizing apparatus), and demographic-majority attainment (Christianity’s territorial rootedness vs. Manichaeism’s permanent diaspora). Christianity’s distinction, on this record, is not that it holds more mechanisms than its rivals but that it held all four of these at once, for most of its history, in most of its range.

5. TAME Agency Assessment

Applying the criteria of this series’ framework paper (Paper 1.1) to the record above:

Goal-directedness (equifinality). The system reaches propagation and self-preservation through radically different means across environments — absorption under Gregory, elasticity under Leo XIII and Pius XII, migration under secularization — the many-paths-one-endpoint signature that goal-directed description tracks.

Problem-space navigation. The six threat classes are six regions of a problem space; §2 documents distinct, environment-appropriate responses in each.

Error correction. Claims that become liabilities are conceded (the cosmological retreats of §2.4); institutional forms that fail are replaced (the state-church losses of §2.5 absorbed by the growth of other branches).

Memory. The deep structure of §6 persists across two millennia of surface transformation — including across complete substrate exchanges (§2.5, §4.2).

Stress response. Under threat, conservative branches intensify collective stress-signaling and cohesion (§2.5), the dynamic modeled in Paper 1.2.

Internal communication. The system maintains dense binding signal traffic across its span and its history — liturgy, scripture, preaching, catechesis, and the martyr commemorations of §2.1, feast-days that function as standing messages.

Trans-host coordination (the further condition of Paper 1.1, §3.2). The system coordinates behavior across billions of hosts in ways that serve system propagation over individual host fitness — missionary sacrifice, celibate clergy, martyrdom, institutional tithing.

On the framework’s criteria this supports the Level 3 (Autonomous) classification proposed in Paper 1.1. The classification is operational, not metaphysical: it claims that treating Christianity as a goal-directed system navigating a fitness landscape yields better predictions of its historical behavior than treating it as a passive aggregate of individually held beliefs — §7.1 names the predictions — not that the system is conscious, and not that it was designed.

6. Deep Structure and Surface Features

6.1 The Invariant Core

Beneath the surface transformations, four structural elements recur across the tradition’s span. Stated carefully — as structural presence, with construal that varies in depth — they are:

• External epistemic authority: truth located outside the individual believer — in scripture, hierarchy, or magisterium — in every major branch, however differently weighted (sola scriptura against conciliar tradition is a dispute about which external authority, not about whether).
• A sin-and-judgment frame: a baseline account of the human as fallen or estranged, subject to judgment, in need of remedy the individual cannot self-supply.
• A system-mediated remedy that renews its own necessity: confession and absolution, repentance and restoration — the relief circuit whose documented fourth-century installation §2.1 recounts (Bryant’s “restorative access”) and whose formal model is Paper 2.2’s.
• A propagation commitment: “Go therefore and make disciples of all nations” (Matt 28:19, Revised Standard Version) — an active conversion mandate paired with exclusive truth-claims, a combination Christianity shares with Islam and, historically, with Manichaeism (§7.2), and which therefore distinguishes it from absorptive traditions without being unique; plus, on this paper’s proposal, the reproduction component of mechanism 8 — expansion through the family as well as through the mission field.

One tradition tests the second element at depth, and the test should be faced rather than footnoted. Eastern Orthodox soteriology centers on theosis — transformative participation in the divine life (Russell, 2006, is the standard doctrinal history) — and its modern theologians distinguish ancestral sin, inherited mortality and corruption, from the Augustinian West’s inherited guilt; on that construal the “disease” is estrangement and death rather than juridical liability, and the “cure” is transformative rather than forensic (Ware, 1963; Meyendorff, 1974). In the vocabulary of this series’ clinical taxonomy (Paper 1.4), that is plausibly a different value on the guilt-installation dimension — a depth variant, not a change of vestments. Two qualifications keep the point in bounds. Orthodoxy retains every other element in full: sacramental confession, sin, judgment, ascetic repentance, external hierarchical authority. And, on a recent analysis, the sharpest form of the East/West contrast is itself substantially a twentieth-century articulation, advanced polemically by the Neo-Patristic movement against the Catholic West (López Cambronero, 2023) — a live doctrinal position, not a stable thousand-year divergence. The right conclusion for a dimensional framework is not that the invariance claim fails but that it was always a claim about structure with graded construal: the four elements are present across branches, and their intensity — most visibly the guilt component — varies at depth. A framework whose taxonomy is dimensional (Paper 1.4) should predict that, and does. The boundary evidence of §2.4 belongs here too: when Humani Generis forbade polygenism because original sin requires “an individual Adam,” the system marked, in a magisterial text, which element of the core is load-limiting for the Latin West.

6.2 Variable Surface Features

What has changed — cosmological claims, liturgical forms, aesthetics, institutional structures, political alignments, ethical emphases — is what the pattern-persistence model of Paper 1.1 designates substrate: rebuildable implementation, replaced repeatedly while the deep structure re-instantiates. The century-scale demographic exchange of §2.5 is the same relation at the level of populations.

7. Limitations and Objections

7.1 The Functionalist Objection

Any system that persisted two millennia will exhibit persistence-compatible features; is the analysis circular? The answer is that the framework does more than curate survivals: it identifies mechanisms, compares them across systems including failed ones (§7.2), and generates predictions that could fail. Four, from this paper’s own material:

1. Institutional continuity under conquest. Where a conquered population retains a functioning supra-local religious institution, religious identity persists at rates qualitatively higher than where the institution is decapitated (the Vryonis contrast, §4.2, generalized). Paired historical cases beyond Anatolia/Balkans can test it; comparable persistence rates regardless of institutional condition would count against it.
2. Dormancy is recoverable only with an external carrier. Communities driven underground re-emerge as themselves only where a pattern-carrier survives outside the suppressed zone; where none does, camouflage becomes absorption (the Japanese case of the seventeenth century and the Chinese Manichaean case — Paper 2.3 takes up the first; §7.2 notes the second). A community re-emerging as itself after generations of dormancy with no surviving external carrier would kill it.
3. Family capture predicts differential persistence. Among comparable contemporary movements, those that capture household transmission (mechanism 8) will outlast adult-recruitment movements of similar size — testable on the extensive data for new religious movements; comparable persistence in adult-recruitment movements, or no differential once founding-cohort age structure is controlled, would count against the mechanism.
4. Response to measured share decline. If the framework’s stress-response claim is right, the first sustained decade of global share loss (Hackett et al., 2025) should be followed, observably and within years, by intensified stress-signaling in conservative branches and accelerated substrate migration — digital and geographic — rather than by uniform accommodation; a decade of uniform accommodation, without intensification or migration, would count against the claim.

The survivorship worry also has a direct partial antidote in the one dataset where cost-and-persistence claims were tested against a full population of failures: the commune record of §2.1, where eighty-two of eighty-three systems died and the cost–longevity relation held only for the religious ones (Sosis & Bressler, 2003).

7.2 The Selection-Bias Objection — Answered by Running the Comparison

Analyzing only a survivor biases the mechanism inventory. The mitigation is to compare systems that did not survive. Three cases, each carrying a different lesson, and none running on the axis a naive mechanism-count would predict.

Manichaeism is the sharpest control because it scores high on this paper’s mechanisms. Mani’s own commissioning, as preserved in the Cologne Mani Codex, is universal (“You have not only been sent to this religion [of the Baptists], but to every people, every school, every town and place”), and the specialist judgment is that “hardly any other religion has undertaken its missionary activities … in a better designed and more systematic way than the Manichean church” (Sundermann, 2009). Its absorption capacity exceeded Christianity’s: it deliberately renamed its pantheon into Zoroastrian, Buddhist, and Taoist registers as it moved — syncretism as engineered technique — and its texts crossed nine languages, spreading “from the Atlantic Ocean to the China Sea” (Sundermann, 2009). It even secured state patronage, twice: the Uighur khaganate from 762/63, and the kingdom of Qočo for about a century and a half. It died everywhere anyway. What it lacked: first, majority roots — “wherever Manichean communities were established, they remained small minority groups. Living in the diaspora was the never-ending, universal fate of the Manicheans” (Sundermann, 2009). Second, institutional redundancy: when the Uighur empire collapsed in 840, the Chinese proscription of 843 followed within three years, with temples closed and clergy executed (Lieu, 2002) — one patron, one collapse, no second implementation to fall back on. Third, universal state hostility with the destruction of its canon written into law: the Diocletianic rescript (dated 31 March of either 297 or 302) ordered the leaders “together with their abominable writings, burned in the flames” — and the corpus was in fact so thoroughly destroyed that the religion had to be reconstructed by modern archaeology. In the West, Brown’s (1969) reading adds the substrate dimension: the religion withered as the cosmopolitan, mobile, trans-imperial society it was adapted to itself disappeared — a pattern with no second substrate there to migrate to. Its long Chinese coda is instructive rather than consoling: surviving by camouflage inside Buddhist and Taoist forms — at one point slipping its scriptures into the Taoist canon (1019, later expunged) — it persisted in Fujian perhaps to about 1600 as an organized religion, with residual cult practice into the early twentieth century (Lieu, 1992, 2002). Dormancy without any surviving external carrier is absorption on a delay: the camouflage became the thing itself. The contrast with Japan’s hidden Christians, who re-emerged after 250 years because an external Christianity still existed to re-emerge into, belongs to Paper 2.3’s transmission analysis.

The Roman mystery cults are the cleanest structural contrast, because the two leading authorities draw it themselves. Mithraism had no scripture, no supra-local organization — “There were no Mithraic bishops; the contrast with contemporaneous Christianity … could not be more extreme” — congregations capped at the size of a cave-room dining bench (“a religion of small communities”), no women, and membership that supplemented rather than replaced civic religion: “as a Mithraist, you would expect, and be expected, to continue your participation in the public cults” (Beck, 2002; see Beck, 2006, for the full treatment). Non-exclusive in allegiance though socially restricted in entry, the mysteries were an add-on to the civic-religious substrate; when imperial legislation dismantled public paganism in the late fourth century, they did not lose a competition — the niche they occupied was abolished beneath them, and nothing in their structure permitted migration. Burkert’s verdict (§3) locates the decisive Christian difference in the self-reproducing ekklesia. Two disciplines follow. The nineteenth-century conceit that Mithraism nearly won — Renan’s fancy — fails on these structural facts without needing rhetoric. And the mysteries should not be described as failures: they did what they were built to do for centuries and ended when their host society did; reading that as competitive defeat is the survivorship error in reverse.

Catharism tests §2.1’s boundary claim, and the historiography must come first: whether an organized dualist counter-church existed in Languedoc at all is a live dispute among the leading medievalists — the deconstruction case (Pegg, 2001; Moore, 2012) against the defense of the traditional picture (Biller, 2016), collected in Sennis (2016) — and Moore’s own summary is that the question has “proved not to be susceptible of resolution by the ordinary procedures of historical method alone,” while the two sides share “a surprising degree of agreement on such facts as are capable of being established” (Moore, 2016, pp. 257, 273). Those establishable facts suffice here: a crusade from 1209, an inquisition operating for roughly a century, the fall of the last strongholds, and by the early fourteenth century the end of the dissenting community — whatever exactly it had been. On the traditional reading, a structured rival church with a martyr ethic was annihilated by sustained force; on the skeptical reading, the persecuting apparatus destroyed — and partly defined into existence — a diffuse local religiosity, which is, if anything, stronger evidence of what totalizing force can do. Either way: force at annihilation intensity, applied over generations, by an apparatus combining military conquest, legal machinery, and control of the successor institutions, with no adjacent refuge, ended the community. Martyrdom leverage has a threshold, a time constant, and a refuge condition (§2.1), and Languedoc is where all three are visible.

What the three cases jointly show. Mechanism inventories are not additive fitness. Manichaeism had the mandate, the mission, and the absorption toolkit, and died of missing redundancy and missing majorities; the mysteries had longevity and prestige and died of a missing growth architecture; Languedoc shows the force-majeure boundary of the best defensive mechanism. The variables that discriminate are the four of §4.5 — which is why this paper retired its scorecard.

7.3 The Intentional-Design Objection

Does the appearance of design in these mechanisms imply a designer? The paper’s answer is deliberately double-edged. No: undirected cultural selection is sufficient in principle to produce every mechanism described, and the historians of the early period describe its greatest strategic success in exactly those terms — “The success of the strategy was discovered only over time; it was not purposively invented as a marketing device” (Hopkins, 1998, on exclusivist belief-policing); the Church “had adventitiously hit upon a world-winning formula” (Bryant, 2023, on penitential leniency). And also no to the opposite inference: the record documents deliberate, dated, self-aware engineering of these mechanisms by human agents — Gregory’s absorption instruction of 601 (§2.3) is applied conversion psychology with a stated rationale and a cited precedent, and the later institutional apparatus of directed propagation is documented in this series’ capstone (Paper 5.1, §2.2). What the record does not permit is a partition: how much of the system’s optimization is drift, how much is human design, cannot be recovered from the outcome, because both processes ran concurrently for twenty centuries and their products are indistinguishable in retrospect. The claim this paper makes is therefore underdetermination — no designer is required, several human designers are documented, and nothing stronger follows in either direction from the adaptations themselves.

8. Conclusion

Read as a complex adaptive system, Christianity’s two millennia yield a disciplined inventory: absorption documented at the level of practice, site, and policy; elasticity documented in the system’s own texts, together with its self-declared boundary at the guilt architecture; persecution converted to growth below a threshold that the Languedoc record locates; schism functioning as portfolio; institutional redundancy tested by its presence in the Balkans and its absence in Anatolia; a substrate exchanged at civilizational scale over one measured century; and a reproduction engine — the family as transmission unit — that the taxonomy of threat responses would have missed and that this paper proposes as its eighth mechanism.

The analysis supports the framework classification of Christianity as a Level 3 autonomous memeplex (Paper 1.1): the claim that its historical behavior is better predicted by goal-directed description than by treating it as an inert belief aggregate — a claim whose test §7.1’s predictions state. The classification is structural, not moral, and not metaphysical. It does not evaluate the tradition’s truth claims; it does not require, and cannot establish, a designer. What it registers is that the system’s architecture — external authority, a sin-and-remedy loop installed early and documented in the act of installation, an exclusive propagation commitment running through mission field and family alike — has made it the hardest kind of system to kill: one that benefits from being attacked, within the limits the extinct cases define, and that rebuilds itself on new substrates when old ones are lost. Whether that persistence serves the interests of its hosts, or primarily its own, is the question this paper hands, unanswered, to the papers built to address it (Papers 1.4 and 2.2).

References

External literature (each entry carries a verification record in the project archive — journal articles at fetch level, several at full-text level; books at book level; entries print only archive-held fields)

• Abdel Haleem, M. A. S. (Trans.). (2004). The Qur’an. Oxford University Press.
• Adang, C. (2000). Islam as the inborn religion of mankind: The concept of fiṭra in the works of Ibn Ḥazm. Al-Qanṭara, 21(2), 391 ff. DOI 10.3989/alqantara.2000.v21.i2.435.
• Amar, A. S. (2019). Reassessing the Muslim attacks and the decline of Buddhist monasteries in the thirteenth century Magadha. In Encountering Buddhism and Islam in Premodern Central and South Asia (pp. 48–74). De Gruyter. DOI 10.1515/9783110631685-003.
• Atran, S., & Henrich, J. (2010). The evolution of religion: How cognitive by-products, adaptive learning heuristics, ritual displays, and group competition generate deep commitments to prosocial religions. Biological Theory, 5(1), 18–30. DOI 10.1162/biot_a_00018.
• Bayliss, R. (2004). Provincial Cilicia and the Archaeology of Temple Conversion (BAR International Series 1281). Archaeopress.
• Beck, R. (2002). Mithraism. In Encyclopædia Iranica (online ed.; article updated 2012).
• Beck, R. (2006). The Religion of the Mithras Cult in the Roman Empire: Mysteries of the Unconquered Sun. Oxford University Press.
• Biller, P. (2016). Goodbye to Catharism? In A. Sennis (Ed.), Cathars in Question (pp. 274–313). York Medieval Press / Boydell Press.
• Bradshaw, P. F. (2020). The dating of Christmas. In T. Larsen (Ed.), The Oxford Handbook of Christmas (pp. 2–14). Oxford University Press. DOI 10.1093/oxfordhb/9780198831464.013.2.
• Bradshaw, P. F., & Johnson, M. E. (2011). The Origins of Feasts, Fasts, and Seasons in Early Christianity (Alcuin Club Collections 86). SPCK / Liturgical Press.
• Brady, W. J., Wills, J. A., Jost, J. T., Tucker, J. A., & Van Bavel, J. J. (2017). Emotion shapes the diffusion of moralized content in social networks. Proceedings of the National Academy of Sciences, 114(28), 7313–7318. DOI 10.1073/pnas.1618923114.
• Bronkhorst, J. (2011). Buddhism in the Shadow of Brahmanism (Handbook of Oriental Studies). Brill.
• Brown, P. (1969). The diffusion of Manichaeism in the Roman Empire. Journal of Roman Studies, 59, 92–103. DOI 10.2307/299850.
• Bruce, S. (1999). Choice and Religion: A Critique of Rational Choice Theory. Oxford University Press.
• Bryant, J. M. (1993). The sect-church dynamic and Christian expansion in the Roman Empire: Persecution, penitential discipline, and schism in sociological perspective. The British Journal of Sociology, 44(2), 303 ff. DOI 10.2307/591221.
• Bryant, J. M. (2023). Decius & Valerian, Novatian & Cyprian: Persecution and schism in the making of a Catholic Christianity — Parts I and II. Athens Journal of History, 9(2), 125–158, 159–184. DOIs 10.30958/ajhis.9-2-1, 10.30958/ajhis.9-2-2.
• Burkert, W. (1987). Ancient Mystery Cults (Carl Newell Jackson Lectures). Harvard University Press.
• Campbell, H. A. (Ed.). (2013). Digital Religion: Understanding Religious Practice in New Media Worlds. Routledge.
• Chaves, M., & Gorski, P. S. (2001). Religious pluralism and religious participation. Annual Review of Sociology, 27(1), 261–281. DOI 10.1146/annurev.soc.27.1.261.
• Cohen, G. A. (1999). Marxism after the collapse of the Soviet Union. The Journal of Ethics, 3(2), 99–104. DOI 10.1023/A:1009825115756.
• Colgrave, B., & Mynors, R. A. B. (Eds. & Trans.). (1969). Bede’s Ecclesiastical History of the English People (Oxford Medieval Texts). Clarendon Press.
• Corke-Webster, J. (2023). By whom were early Christians persecuted? Past & Present, 261(1), 3–46. DOI 10.1093/pastj/gtac041.
• Cristini, M. (2025). The Years of the Infidels: African Latin Christianity from the Vandals to the Almohads. Routledge. DOI 10.4324/9781003414988.
• Crockett, M. J. (2017). Moral outrage in the digital age. Nature Human Behaviour, 1(11), 769–771. DOI 10.1038/s41562-017-0213-3.
• de Ste. Croix, G. E. M. (1963). Why were the early Christians persecuted? Past & Present, 26(1), 6–38. DOI 10.1093/past/26.1.6. (Reprinted with the 1964 rejoinder in Christian Persecution, Martyrdom, and Orthodoxy, Oxford University Press, 2006.)
• Ghosh, S. (2022). Patronage of Buddhist monasteries in eastern India (600–1300 CE). In Oxford Research Encyclopedia of Religion. DOI 10.1093/acrefore/9780199340378.013.811.
• Gould, S. J. (1997). Nonoverlapping magisteria. Natural History, 106(March), 16–22.
• Gould, S. J. (1999). Rocks of Ages: Science and Religion in the Fullness of Life (The Library of Contemporary Thought). Ballantine Publishing Group.
• Hackett, C., Stonawski, M., Tong, Y., Kramer, S., Shi, A., & Fahmy, D. (2025). How the Global Religious Landscape Changed From 2010 to 2020. Pew Research Center. DOI 10.58094/fj71-ny11.
• Henrich, J. (2009). The evolution of costly displays, cooperation and religion: Credibility enhancing displays and their implications for cultural evolution. Evolution and Human Behavior, 30(4), 244–260. DOI 10.1016/j.evolhumbehav.2009.03.005.
• Hopkins, K. (1998). Christian number and its implications. Journal of Early Christian Studies, 6(2), 185–226. DOI 10.1353/earl.1998.0035.
• Inglehart, R. F. (2021). Religion’s Sudden Decline: What’s Causing It, and What Comes Next? Oxford University Press.
• Jenkins, P. (2002). The Next Christendom: The Coming of Global Christianity. Oxford University Press.
• John Paul II. (1996, October 22). Message to the participants in the plenary of the Pontifical Academy of Sciences. Vatican.
• Johnson, T. M., & Zurlo, G. A. (2019). World Christian Encyclopedia (3rd ed.). Edinburgh University Press.
• Knipfing, J. R. (1923). The libelli of the Decian persecution. Harvard Theological Review, 16(4), 345–390. DOI 10.1017/s0017816000013791.
• Kretzmann, N., Kenny, A., Pinborg, J., & Stump, E. (Eds.). (1982). The Cambridge History of Later Medieval Philosophy: From the Rediscovery of Aristotle to the Disintegration of Scholasticism, 1100–1600. Cambridge University Press.
• Kuiper, M. J. (2021). Da’wa: A Global History of Islamic Missionary Thought and Practice (The New Edinburgh Islamic Surveys). Edinburgh University Press.
• Leo XIII. (1893, November 18). Providentissimus Deus [Encyclical]. Vatican.
• Lieu, S. N. C. (1992). Manichaeism in the Later Roman Empire and Medieval China (2nd, revised and extended ed.; Wissenschaftliche Untersuchungen zum Neuen Testament 63). J. C. B. Mohr (Paul Siebeck). (1st ed., Manchester University Press, 1985.)
• Lieu, S. N. C. (2002). Manicheism vi. In China. In Encyclopædia Iranica (online ed.; article updated 2018).
• López Cambronero, M. (2023). Evil and guilt: On original sin and ancestral sin. Cauriensia, 18, 525–540. DOI 10.17398/2340-4256.18.525.
• MacMullen, R. (1984). Christianizing the Roman Empire (A.D. 100–400). Yale University Press.
• MacMullen, R. (1997). Christianity and Paganism in the Fourth to Eighth Centuries. Yale University Press.
• Markus, R. A. (1970). Gregory the Great and a papal missionary strategy. Studies in Church History, 6, 29–38. DOI 10.1017/S0424208400004836.
• Martyn, J. R. C. (Trans.). (2004). The Letters of Gregory the Great (3 vols.; Mediaeval Sources in Translation 40). Pontifical Institute of Mediaeval Studies.
• Meyendorff, J. (1974). Byzantine Theology: Historical Trends and Doctrinal Themes. Fordham University Press.
• Moore, R. I. (2012). The War on Heresy: Faith and Power in Medieval Europe. Profile Books.
• Moore, R. I. (2016). Principles at stake: The debate of April 2013 in retrospect. In A. Sennis (Ed.), Cathars in Question (pp. 257–273). York Medieval Press / Boydell Press.
• Nothaft, C. P. E. (2012). The origins of the Christmas date: Some recent trends in historical research. Church History, 81(4), 903–911. DOI 10.1017/S0009640712001941.
• Pegg, M. G. (2001). On Cathars, Albigenses, and good men of Languedoc. Journal of Medieval History, 27(2), 181–195. DOI 10.1016/S0304-4181(01)00008-2.
• Pew Research Center. (2011, December 19). Global Christianity: A Report on the Size and Distribution of the World’s Christian Population. Pew Research Center’s Forum on Religion & Public Life.
• Philippi, T., & Seger, J. (1989). Hedging one’s evolutionary bets, revisited. Trends in Ecology & Evolution, 4(2), 41–44. DOI 10.1016/0169-5347(89)90138-9.
• Pius XII. (1950, August 12). Humani Generis [Encyclical]. Vatican.
• Rappaport, R. A. (1999). Ritual and Religion in the Making of Humanity (Cambridge Studies in Social and Cultural Anthropology). Cambridge University Press.
• Richerson, P. J., & Boyd, R. (2005). Not by Genes Alone: How Culture Transformed Human Evolution. University of Chicago Press.
• Rist, J. M. (1994). Augustine: Ancient Thought Baptized. Cambridge University Press. DOI 10.1017/CBO9780511520228.
• Rives, J. B. (1999). The decree of Decius and the religion of empire. Journal of Roman Studies, 89, 135–154. DOI 10.2307/300738.
• Russell, N. (2006). The Doctrine of Deification in the Greek Patristic Tradition. Oxford University Press.
• Sellar, A. M. (Trans.). (1907). Bede’s Ecclesiastical History of England: A Revised Translation. George Bell and Sons.
• Sennis, A. (Ed.). (2016). Cathars in Question (Heresy and Inquisition in the Middle Ages 4). York Medieval Press / Boydell Press.
• Shaw, P. A. (2011). Pagan Goddesses in the Early Germanic World: Eostre, Hreda and the Cult of Matrons. Bristol Classical Press.
• Simons, A. M. (2011). Modes of response to environmental change and the elusive empirical evidence for bet hedging. Proceedings of the Royal Society B: Biological Sciences, 278(1712), 1601–1609. DOI 10.1098/rspb.2011.0176.
• Sosis, R., & Alcorta, C. S. (2003). Signaling, solidarity, and the sacred: The evolution of religious behavior. Evolutionary Anthropology, 12(6), 264–274. DOI 10.1002/evan.10120.
• Sosis, R., & Bressler, E. R. (2003). Cooperation and commune longevity: A test of the costly signaling theory of religion. Cross-Cultural Research, 37(2), 211–239. DOI 10.1177/1069397103037002003.
• Spiegel, F. (2007). The tabernacula of Gregory the Great and the conversion of Anglo-Saxon England. Anglo-Saxon England, 36, 1–13. DOI 10.1017/S0263675107000014.
• Stark, R. (1996). The Rise of Christianity: A Sociologist Reconsiders History. Princeton University Press.
• Stark, R., & Finke, R. (2000). Acts of Faith: Explaining the Human Side of Religion. University of California Press.
• Sundermann, W. (2009). Manicheism v. Missionary activity and technique. In Encyclopædia Iranica (online ed.; article updated 2018).
• Voas, D., Olson, D. V. A., & Crockett, A. (2002). Religious pluralism and participation: Why previous research is wrong. American Sociological Review, 67(2), 212–230. DOI 10.1177/000312240206700203.
• Vryonis, S., Jr. (1971). The Decline of Medieval Hellenism in Asia Minor and the Process of Islamization from the Eleventh through the Fifteenth Century (Publications of the Center for Medieval and Renaissance Studies, UCLA, 4). University of California Press.
• Wallis, F. (Trans.). (1999). Bede: The Reckoning of Time (Translated Texts for Historians 29). Liverpool University Press.
• Ware, T. (1963). The Orthodox Church (Pelican Books A592). Penguin.
• Wilson, D. S. (2002). Darwin’s Cathedral: Evolution, Religion, and the Nature of Society. University of Chicago Press.
• Zurlo, G. A., Johnson, T. M., & Crossing, P. F. (2025). World Christianity 2025: Regional perspectives. International Bulletin of Mission Research, 49(1), 62–74.

The series

• Grünig, P., & Claude Fable (Anthropic). (2026). Memeplexes as Adaptive Cognitive Systems: A TAME-Integrated Framework for Understanding Ideological Agency. Paper 1.1 of this series (rev. 2, August 2026). Project archive. [cited as Paper 1.1]
• Grünig, P., & Claude Fable (Anthropic). (2026). Stress-Sharing as Cognitive Glue in Ideological Collectives: From Biological Morphogenesis to Cultural Cohesion. Paper 1.2 of this series (rev. 2, August 2026). Project archive. [cited as Paper 1.2]
• Grünig, P., & Claude Fable (Anthropic). (2026). Religious Belief Systems and Mental Health Outcomes: A Structural Taxonomy Distinguishing Architecture from Content. Paper 1.4 of this series (rev. 2, September 2026). Project archive. [cited as Paper 1.4]
• Grünig, P., & Claude Fable (Anthropic). (2026). The Luciferian Hypothesis: A Scientific Reinterpretation of the Panakal Thesis. Paper 5.1 of this series (rev. 2, August 2026). Project archive. [cited as Paper 5.1]

Classical and scriptural primary sources are cited in text: Origen, Contra Celsum (Ante-Nicene Fathers translation); Cyprian, Epistulae and the associated documentation as quoted in Bryant (2023); the Diocletianic rescript at Collatio legum Mosaicarum et Romanarum 15.3 (Hyamson translation, as adapted by Harland); Gregory the Great, Registrum XI.56 (Norberg’s critical edition, CCSL 140–140A, 1982, underlies the Martyn translation cited above); Bede, Historia ecclesiastica i.30, i.32, ii.4 and De temporum ratione 15; Matt 28:19 (Revised Standard Version); Qur’an 2:37, 6:164, 20:122, 30:30, and 35:18 in the Abdel Haleem translation listed above.

Note: This paper applies the framework developed in Papers 1.1 (memeplex–TAME integration) and 1.2 (stress dynamics), uses the architectural vocabulary of Paper 1.4, and hands its open questions to Papers 2.2 (dependency modeling), 2.3 (transmission architectures), and 5.1 (the design question). It is the bridge between the general theory of Phase 1 and the analytical papers of Phase 2.