Book Review: The Rise Of Christianity

The rise of Christianity is a great puzzle. In 40 AD, there were maybe a thousand Christians. Their Messiah had just been executed, and they were on the wrong side of an intercontinental empire that had crushed all previous foes. By 400, there were forty million, and they were set to dominate the next millennium of Western history.

Imagine taking a time machine to the year 2300 AD, and everyone is Scientologist. The United States is >99% Scientologist. So is Latin America and most of Europe. The Middle East follows some heretical pseudo-Scientology that thinks L Ron Hubbard was a great prophet, but maybe not the greatest prophet.

This can only begin to capture how surprised the early Imperial Romans would be to learn of the triumph of Christianity. At least Scientology has a lot of money and a cut-throat recruitment arm! At least they fight back when you persecute them! At least they seem to be in the game!

Rodney Stark was a sociologist of religion. He started off studying cults, and got his big break when the first missionaries of the Unification Church (“Moonies”) in the US let him tag along and observe their activities. After a long and successful career in academia, he turned his attention to the greatest cult of all and wrote The Rise Of Christianity. He spends much of it apologizing for not being a classical historian, but it’s fine - he’s obviously done his homework, and he hopes to bring a new, modern-religion-informed perspective to the ancient question.

So: how did early Christianity win?

Slowly But Steadily

Previous authorities assumed Christianity spread through giant mass conversions, maybe fueled by miracles. Partly they thought this because the Biblical Book of Acts describes some of these. But partly they thought it because - how else do you go from a thousand people to forty million people in less than 400 years?

Stark answers: steady exponential growth.

Suppose you start with 1,000 Christians in 40 AD. It’s hard to number the first few centuries’ worth of early Christians - they’re too small to leave much evidence - but by 300 AD (before Constantine!) they’re a sizeable enough fraction of the empire that some historians have tentatively suggested a 10% population share. That would be about 6 million people.

From 1,000 to 6,000,000 in 260 years implies a 40% growth rate per decade. Stark finds this plausible, because it’s the same growth rate as the Mormons, 1880 - 1980 (if you look at the Mormons’ entire history since 1830, they actually grew a little faster than the early Christians!)

Instead of being forced to attribute the Christians’ growth to miracles, we can pin down a specific growth rate and find that it falls within the range of the most successful modern cults. Indeed, if we think of this as each existing Christian having to convert 0.4 new people, on average, per decade, it starts to sound downright do-able.

Still, how did the early Christians maintain this conversion rate over so many generations?

Through The Social Graph

This is another of Stark’s findings from his work with the Moonies.

The first Moonie in America was a Korean missionary named Young Oon Kim, who arrived in 1959. Her first convert was her landlady. The next two were the landlady’s friends. Then came the landlady’s friends’ husbands and the landlady’s friends’ husbands’ co-workers. That was when Stark showed up. “At the time . . . I arrived to study them, the group had never succeeded in attracting a stranger.”

Stark theorized that “the only [people] who joined were those whose interpersonal attachments to members overbalanced their attachments to nonmembers.” I don’t think this can be literally correct - taken seriously, it implies that the second convert could have no other friends except the first, which would prevent her from spreading the religion further. But something like “your odds of converting are your number of Moonie friends, divided by your number of non-Moonie friends” seems to fit his evidence.

History confirms this story. Mohammed’s first convert was his wife, followed by his cousin, servant, and friend. Joseph Smith’s first converts were his brothers, friends, and lodgers. Indeed, in spite of the Mormons’ celebrated door-knocking campaign, their internal data shows that only one in a thousand door-knocks results in a conversion, but “when missionaries make their first contact with a person in the home of a Mormon friend or relative of that person, this results in conversion 50% of the time”. 1

This theory of social-graph-based-conversation was controversial when Stark proposed it, because if you ask cultists retrospectively, they’ll usually say they were awed by the beauty of the sacred teachings. But Stark says:

I knew better, because we had met them well before they had learned to appreciate the doctrines, before they had learned how to testify to their faith, back when they were not seeking faith at all. Indeed, we could remember when most of them regarded the religious beliefs of their new set of friends as quite odd. I recall one who told me that he was puzzled that such nice people could get so worked up about “some guy in Korea” . . . Then, one day, he got worked up about this guy too.

by Scott Alexander, Astral Codex Ten |  Read more:

Image: uncredited
[ed. There's much more, but I'd also suggest that Christianity benefited from an abundance of scribblers, editors and transcriptionists who, over successive generations, defined and redefined God in the Bible (and Christianity in general) to fit an evolving religion and events of the time. Jack Miles' God: A Biography covers this ground quite thoroughly. See also: this review of the book (Commentary); God: A Biography: Q&A (Jack Miles); and, Christian theology (Wikipedia).]