Time to answer a readers’ question, as a change of pace, unrelated to anything else I’ve been posting on:


The question on my mind is almost certainly NOT knowable, but I will ask it anyway.

1 – can anyone estimate how many Christians (all variations included) were abroad on Planet Earth at any given time in the 100s or 200s?

2 – when Constantine chose to back Christianity and make it the “official” religion — in the early piece of the 300s — how many actual Christians were there? Or, to make it easier: Taking the whole “Roman” empire as 100%, what pct of the peeps were Christians?

3 – A few generations later (380?) — Theodosius I said that the Roman Empire officially believed what the Bishop of Rome believed. How many (or what percentage of the people) were Christians in 379?

I don’t expect precise answers. Any pointers you could provide to where answers might be found (or guesstimates, even) by researchers/experts/theologians/atheists or even hockey players would be appreciated.


This is an excellent question (or set of questions).  It’s not clear if scholars actually know the answers, but they have offered some!    I will give the short answers.  If you are interested in pursuing the matter further, I’d suggest two VERY different books (i.e. different from each other): Ramsey MacMullen, Christianizing the Roman Empire (MacMullen is a social historian of ancient Rome, a real expert in antiquity); and Rodney Stark, The Rise of Christianity (a highly controversial book that was not well received by scholars; Stark is a sociologist of modern religion who tries to apply his craft to the ancient world.  He actually doesn’t know enough about the ancient world to make it work, but as a sociologist he knows how to crunch numbers, and that’s where he’s really interesting).

So, the basic story is this.   There were probably about 60 million inhabitants in the Roman Empire, give or take, throughout the first four centuries CE (the period you’re asking about).  It is almost universally thought that Christianity started out as a  very small movement – say about 20 people a few weeks after Jesus’ death.

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