super long but mildly interesting; it is crazy that this religion went from 1k to 6M followers in 300 years

Cults almost invariably spread through friend networks, never cold converts (src: Moonies and Mormons (who apparently collect great data on this)) Conversion probability is probably roughly proportional to [friends in cult]/[friends not in cult]

Successful cults/religions very often start off with many more women than men (and then presumably the men notice and follow). Checks out with my anecdata

Periodic reminder: life in Rome was absolutely terrible. Extremely cramped, everyone was dying all the time, cities were regularly destroyed by fire, war, etc

Christians caring for each other during plagues gave them great relative mortality rates (10% vs others 30%)

Conclusion though: mostly no explanation here is that compelling vs just noticing that 40% increase per decade is pretty achievable and exponentials get big fast