My Baylor colleague Philip Jenkins has a fascinating post over at the Anxious Bench blog, in which he provides estimates for the number of Christians living in 200 A.D. Citing the work of our mutual Baylor colleague Rodney Stark on the early church, Jenkins notes that Stark

estimated a global Christian population of 40,000 in AD 150, rising to 218,000 in 200, and 1.17 million by 250. According to his calculation, it was around 180 that global Christian numbers first surpassed the symbolically weighty figure of 100,000.

Stark would be the first to admit that those figures are anything but precise, but they provide plausible limits. If someone suggested a Christian population in 200 as ten thousand, or as ten million, then they would assuredly be wrong. But a range anywhere from (say) 150,000 to 350,000 would be quite plausible.

There are some reasons to place the figure for AD 200 a bit higher than Stark proposed. One specific issue concerns the total population with which Stark is working, which is that of the Roman Empire. His estimate for the overall Roman population is rather lower than more recent estimates, and Christian numbers must be adjusted accordingly.

Another wildcard in these numbers, Jenkins notes, is that the Christian world was already badly divided, so some estimates may not take into account groups already regarded as heretical.

For the sake of argument, let us suggest a global Christian population of perhaps 250,000. That represents a stunning expansion from the small groups we glimpse in apostolic times, but the number is tiny when we think of the vast geographical extent of the large world, from Mesopotamia to Britain. It is also a tiny fraction of that world – perhaps 0.36 percent of whole population of the Roman Empire at this time, or one in three hundred…

Even taking the most optimistic view, Christians at this stage were extremely thinly spread.

Overwhelmingly, Christianity was an urban faith, and we recall Tertullian’s boast about “almost all” the city dwellers being Christian. In fact they weren’t, but the remark does suggest how easily Christians might be found in major urban centers. The largest Christian communities were in the six or so leading cities of the Roman Empire, including Rome itself, Carthage, Alexandria, Jerusalem, Ephesus, and Antioch.

Stark has explained the growth of the church in these centuries in books like The Rise of Christianity, and we can look forward to more analysis from Jenkins on these matters, too.

Jenkins concludes his post with a tantalizing observation, given the faith’s small presence in 200 A.D.: “to think that little over a century after that point, Christianity would be the dominant religion in the whole Roman Empire.”

Read the whole post at Patheos.