How likely are liberals and feminists to survive by conversion?

Every now and then I like to challenge left heads by pointing out that they have incredibly low birth rates. The typical retort is that they will survive by educating conservatives. The TFR for liberals is lower than that of conservatives and has been for some time. 

I asked Claude a simple question:

"Other than the Shakers what cults down through history have denied the role of sex in life, shunned reproduction, or been exclusively homosexual? In other words what cults have failed to breed new members or shunned the breeding of new members choosing instead to survive by proselytizing only? Do any of these cults or religious movements still exist? List every single one you can think of then attempt to generate a probability that an ideology can survive by conversion only." 

Here is what Claude said:

"Here's every group I can dig up that fits the pattern — rejected sex/reproduction as spiritually corrupting, or organized itself so that only converts/outsiders' children replenished the ranks:

Ancient and late antique

1. Essenes (and the possibly-related Qumran community) — Jewish ascetics described by Josephus and Philo; at least some branches practiced strict celibacy, adopting outsiders' children instead of breeding. Extinct since antiquity.

2. Therapeutae — Philo's Hellenistic Jewish contemplative sect in Egypt, celibate ascetics. Extinct.

3. Encratites — 2nd-century Christian ascetic movement (associated with Tatian) that rejected marriage and procreation outright as complicity with the fallen material world. Extinct/absorbed.

4. Marcionites — Marcion of Sinope's followers rejected the god of Genesis and discouraged procreation as perpetuating his flawed creation; strict ascetics, though not universally celibate. Suppressed/extinct by the early medieval period.

5. Manichaeans — dualist religion where the elect (as opposed to ordinary "hearers") were celibate, since sex trapped divine light in matter. Survived in fragments in China into the 14th century; extinct as an organized faith now.

Medieval dualists

6. Bogomils — Balkan dualist sect, direct ancestor of the Cathars; their "perfect" adherents were celibate ascetics. Extinct.

7. Cathars (Albigensians) — the perfecti renounced sex and procreation as imprisoning souls in matter; ordinary believers could marry and were only expected to take the vow near death. Wiped out by the Albigensian Crusade and Inquisition; extinct by the 14th century.

Early modern radical Protestant/utopian communes (America, mostly)

8. Ephrata Cloister (Pennsylvania, founded 1732) — German Pietist celibate monastic order, sustained by conversion of nearby Seventh Day Baptist–adjacent communities. Extinct by the mid-19th century.

9. Harmony Society / Harmonists (Rappites) — George Rapp's followers adopted celibacy after 1807, expecting an imminent Second Coming, and grew instead by immigration and conversion from Germany. Dissolved 1905; extinct.

10. Shakers — you excluded them, but worth noting as the textbook case: celibate, sustained entirely by conversion and (later) orphan adoption. Down to a literal handful at Sabbathday Lake, Maine — arguably still technically alive but functionally over.

11. Koreshan Unity (Cyrus Teed's Florida hollow-earth community) — celibate utopians. Last member died in 1982; extinct.

12. Panacea Society (Bedford, England, founded 1919) — millenarian group awaiting the return of "Shiloh," predominantly female and largely celibate. Ceased to exist as a religious community when its last resident member died in 2012.

Russian sectarian extremes

13. Skoptsy ("castrates") — practiced ritual castration of men and mastectomy of women to eliminate sexual desire entirely, recruiting converts (sometimes coercively) rather than reproducing. Formally banned by 1905, decimated further under Soviet repression; believed nearly extinct, though a few writers claim scattered remnants or ideological descendants ("anti-sexuals") persisted into the late 20th/early 21st century in parts of the former USSR and Romania — unverified and almost certainly marginal.

14. Some Bezpopovtsy Old Believer splinter groups (e.g., the Beguny/"Runners") pushed extreme asceticism, including rejection of marriage, though this varied by sub-sect rather than being universal doctrine.

20th-century

15. Heaven's Gate — the UFO/apocalyptic group whose leader Applewhite and several male followers were castrated, and which treated sexuality as an obstacle to "the Next Level." Ended in the 1997 mass suicide; extinct.

Still existing today

16. Brahma Kumaris — a modern Hindu-derived new religious movement (founded 1930s India) that requires strict celibacy (*brahmacharya*) of its members, including married converts, as central practice. Actively growing worldwide today by conversion.

17. Radical Faeries — a loosely organized countercultural/spiritual movement founded in 1979, predominantly gay men, explicitly non-reproductive by demographic composition rather than doctrine, sustained by recruitment/self-identification rather than birth. Still active, though "cult" is a stretch — it's closer to an affinity movement.

18. The Two by Twos (a.k.a. Cooneyites, "the Truth") — itinerant unpaid "workers" take vows of celibacy and poverty, but the lay membership ("friends") marry and reproduce normally, so this is a hybrid model, not a fully non-reproducing group. Still exists globally.

19. Roman Catholic priesthood, and Catholic/Orthodox/Buddhist monasticism generally — not "cults" by any reasonable definition, but the same structural pattern: celibate, no biological reproduction, and yet demonstrably the most durable version of this strategy in history, because it draws its converts from a large surrounding population that keeps breeding and periodically donates children or adults into the celibate order. This distinction matters for your probability question below.

Now, the probability question. I'd break "survival by conversion only" into two very different cases, because they have wildly different odds.

Case A: a closed sect drawing converts only from the general outside population, with no built-in feeder population that reproduces on its behalf. History gives an almost uniformly bad track record — the Shakers, Harmonists, Koreshans, Panacea Society, Skoptsy, Cathars, Ephrata Cloister all eventually died out, typically within one to a few centuries, and often within a single generation once the founding charisma faded, because conversion rates for a doctrine this demanding are inherently low, and each generation has to re-win 100% of its membership from scratch with no demographic cushion. If I had to put a number on it, something like a 1-5% chance any given such sect is still a living, functioning religious community two hundred years after founding, and it trends toward zero the further out you go, because the required net conversion rate to merely hold population steady (let alone grow) is very hard to sustain once the founder is gone and the novelty/persecution dynamics that drove early conversion fade. The Shakers are the closest thing to a counterexample and they're a rounding error away from extinction after roughly 250 years.

Case B: an order embedded inside a larger reproducing tradition that feeds it converts as a matter of course — Catholic and Orthodox monasticism, the Buddhist sangha, arguably Brahma Kumaris riding on Hinduism's demographic base. Here the odds of indefinite survival are much higher, plausibly majority-likely over centuries, because the "conversion" isn't really cold recruitment from a hostile outside world — it's an accepted social institution that a self-reproducing host culture continuously staffs. That's really a different phenomenon from what you're asking about, even though the celibate unit itself doesn't reproduce.

So the short version: a genuinely closed group that must win every single member from an unconverted outside population, with no reproducing base of its own, is a demographic dead end almost by definition — it's playing a game where the required win rate per generation is brutally high and the actual observed win rate for such heterodox, demanding movements is almost always well below replacement. The exceptions that have lasted (institutional monasticism) only last because they've effectively parasitized a fertile host religion rather than surviving purely on stranger-conversion. If you want, I can try to formalize this into an actual demographic model — something like a fertility-vs-conversion-rate threshold equation — rather than eyeballing it."