Christian Population in the Roman Empire

[David Atherton]

Browsing a Roman history forum I belong to, I came across these figures concering the growth of Christianity in the Roman Empire:

Christian Growth Projected at 40 Percent per Decade (Based on an estimated population of 60 million)

40AD.....1,000 Christians.....0.0017% of population
50 ......1,400.....................0.0023%
100 .....7,530....................0.0126%
150 .....40,496...................0.07%
200 .....217,796..................0.36%
250 .....1,171,356................1.9%
300 .....6,299,832...............10.5%
350 .....33,882,008..............56.5%

(From Stark's 'The Rise of Christianity: How the Obscure, Marginal Jesus Movement Became the Dominant Religious Force in the Western World in a Few Centuries')

This has always been of keen interest to me and I was wondering if anyone had any other figures or resources concerning this subject to share?

Glancing through my copies of Macmullen's 'Christianizing The Roman Empire' and Wilken's 'The Christians As The Romans Saw Them' I could not find any comparable Christian population numbers.

[Robert_Brenchley]

I'd be interested to know how Stark worked it out! There simply are no ancient figures, but he may not be far out. I don't think there's any doubt that major growth began in the 3rd Century, during the near collapse of the empire. Gallienus legalised the church, and people must have been looking for new faiths given that the old observances weren't saving the empire from near-disaster. The Great persecution came too late to stop its growth, and by the time of Constantine, it was big enough to be politically useful. Once it was not only legal, but officially favoured, the result was a massive boom in the Christian population.

[Jeff Clark]

These numbers from Stark do not appear to have any significance, other than mathematical, at all.  He started with the premise that shortly after the crucifixion there were only 1000 Christians.  If he started with less or more, the final number would be considerably different.  The final number is reached by multipying the previous value by 1.4 for every 10 year period.  It might by chance be correct, but the mathematics certainly don't make it so!
For every single person away from 1000, it makes 33,882 difference to the final total.  Apparently, it is all just a guess.

[Robert_Brenchley]

I wonder whether it's pure coincidence that he gets the curve in something like the right place, or whether he fiddled his figures. 1000 followers straight after the crucifixion sems a bit high to me. He didn't have enough people at the time for anyone to consider it worth recording whatever exactly it was that happened, and it's a pretty safe bet that most of the people he did have gave up and went home once he was arrested.

The only thing I can think of that this could be based on is Paul's claim that the risen Jesus was seen by over 500 people all at once (1 Corinthians 15:3-8). I do think the claim is rhetorical though. It seems that in order to be accepted as a leader in the early days, you needed to claim a personal appearance.  Paul lists the important people who saw him; Cefas (Peter), the Twelve, James and the apostles. Paul has, of course, quarrelled with Peter and James, though he still has to recognise them as the leaders of the movement. So he adds the 500 to say that these visions aren't really that special after all. Then, of course, he gets to the nitty-gritty; he's seen Jesus himself, so he's as good as they are anyway!

[Heliodromus]

I'd highly recommend Stark's book to anyone interested in topic. I've also read MacMullen's books on the subject, but Stark was still a major eye opener!

As far as the numbers, it depends on what you are looking for. Obviously exact numbers in any year are only an estimate however they are derived, but the pattern of growth has to be roughly as depicted by that chart. Social phenomena grow by contact with outsiders and therefore exhibit exponential growth (i.e. growth isn't fixed in absolute terms but instead depends on the existing membership size - it can be expressed as a percentage of the existing membership).

The size of the Christian population therefore naturally follows an exponential curve (notwithstanding any variation in the exact percentage growth in any given year or period), and the average growth rate is very heavily bounded by the known facts. In 40AD we know that the number of Christians was very small, whether it was 100, 1000 or 10,000 - I'm sure nobody would claim it was 100,000 or larger. Similarly by 350AD we know that Christian's comprised a sizable percentage of the population; it's hard to imagine Theodosius having been able to make Christianity the official state religion if Christians weren't of the order of 50% of the population (i.e. 30,000,000). You could argue the exact number, but again noone is going to suggest that the Christian population in 350AD was less than say 25% or more than say 75%.

The formula for exponential growth is Nt = N0 x (1 + r) ^ t where N0 is the starting size (population), Nt is the population after t periods of growth, and r is the fractional growth rate per period.

e.g. If we assume that  in 40AD N0 = 1000 and r = 3.42% / yr (= 40% / decade), then the population in 350AD would be 1000 * 1.0342^310 = 33,682,581

You can also invert the formula to get the growth rate given the end points:

r = ((Nt / N0) ^ (1/t)) - 1   (as a fraction - multiply by 100 to get a percentage)

So for example:

with a starting population of 100 ending with 30,000,000 after 300 years growth, r = 4.29% / yr

with a starting population of 1000 ending with 30,000,000 after 300 years growth, r = 3.49% / yr

with a starting population of 10000 ending with 30,000,000 after 300 years growth, r = 2.70% / yr

So an annual growth rate of approx 3.5% (= 40% per decade) has to be in the ballpark regardless of the exact starting numbers, and while the precise curve will vary, bottom line is that with an exponential growth rate in that ballbark the curve is always going to be roughly the same if it is the big picture you are looking for.

Interestingly as Stark notes, the 40% / decade (3.42% / yr) growth figure that seems to be in the ballpark for Christianity to have grown to 50% of the population by 350AD is also about the exact same per decade figure that the Mormon religion has grown in the US over the last century (and no doubt that feels quite different whether one is in Utah or New York, just as it would have done in Antioch vs Trier).

Anyway, I highly recommend the book - it's much more than just statistics (the above examples are just my own, not from the book), and there is also much grounding as reality check for the numbers .

Ben

[basemetal]

Very interesting.
I think the early Christian population burgeoned because it's message (post Jerusalem destruction)said something that had not been said after centuries of conquer, kill, sell the survivors into slavery, rape the women first, then sell them, might makes right, you can only be a senior member of this religion(roman and others) if you are born noble, and the guy with the sword always beats the guy with the message.

According to at least the roman religion, no great advantage in leading a "good" life (this was more directed at the rulers and masters-not the slave population), we all go to the underworld (I know-elysium-but that is only for Romans).

Here comes a religion that basically says: "You get off the hook because Christ has atoned for your sins by dying for you.  Accept him as your savior(the guy who did all the suffering for you and you have a clean slate). Worship him.  Tell others about it (a big part of it).

You may be a slave, but in the eyes of God, you are equal to the richest and most powerful of men. You don't have armies or weapons, excluding your faith.  That is enough to gain eternal life.  Even the most humble(read lowest class) are equal in the eyes of God. Sounds like a good rap to recruit to me.

Subsequent history shows that Christians, being human, quickly established hierarchies in this message.  But not at first. What it takes to succeed is a lot of lower class, which the roman empire had.  

Whatever the graphs show, I'm not surprised that it was a compelling message and spread quickly
Bruce

[Heliodromus]

According to Stark, one of the things that studies of growth of modern religion shows is that belief typically follows membership rather than vice versa - membership comes about more because of a critical mass of friends and family being in a new religion, and this type of network growth was likely as true back then as it is now.

It seems that quite a large part of the success of Christianity was being in the right place at the right time - the Jewish vs Roman clash of civilizations occuring at the same time as the Roman population was losing faith in their own religion due the the hard time the empire had been going thru and the apparent failure of the gods to protect them. Stark shows quite convincingly (incl. archaelogical evidence - churches & synagogues closely associated) that the early spread of Christianity was among the Jews of the diaspora who had become partially romanized and outcasts from their own religion, yet more attracted to it (and the closely related early Christianity) than the religio romana. Without these initial easy converts Christianity may never have crossed over into the Roman population in great enough numbers to take hold.

As Christianity spread the message itself may have been attractive, but it was likely the practical application of the message that was really effective and helped Christianity grow not only in absolute numbers but as a percentage of the population. If you consider the approx. 3.5% annual growth rate of Christianity, the birth rate must have been an appreciable part of that, and so the Christian aversion to exposure of unwanted children (prevalent among the Romans) must have had a significant effect over time as Stark notes. Also Christian traditions of care giving (later noted as significant by Julian II) would have helped the sick survive and this may have been quite a significant effect (percentage of population boost) especially during the two major epidemics of the first few centuries (one, maybe smallpox, during the time of Marcus Aurelius wiped out 1/4-1/3 of the entire population, and another, maybe measels, did similar damage c. 251).

Ben

[gavignano]

I was just typing in the concept of critical mass when Ben typed in a great post. For example, individual events in the Empire, in relation to Christians as part of the population, is fascinating. If one can go along with the history of Nero attempting to blame the Christians at the time of the Great Fire, then there must have been a decent number in Rome proper, not including any other rapid expansion in the areas of the diaspora. You don't blame a marginal movement, but you do blame one that seems to be growing at noticeable, even alarming, rates.
I know many long time posters here are athiests or agnostics, and the majority are certainly non Christians, but the rise of this faith looks like a rather stunning example of precise timing, whatever the driving force 

[Robert_Brenchley]

There's no evidence of large numbers of Christians in Rome that early; not so long before, Paul had written to the church there, and refers to a guy called Gaius as 'host to the whole church' implying that they could all meet in his house. The surprising thing is that they should have come to official notice at all. The most likely thing is that they'd offended some of the stricter Jews in the city, and been informed on.

[Heliodromus]

The absolute numbers of Christians wouldn't have been very large in Rome that early, but it's the nature of big cities (a consequence of "connectedness" I suppose - a high level of traffic in and out, and high population density) that new trends take hold there first before spreading into more remote or sparsely populated areas. At least one contemporary author noted this fact. So, while Nero's Rome may not have had a large Christian population is would likely still have been larger than one might have guessed from it's geographical location (distance from Judea). Further, in rejecting the state religion that was seen as necessary to keep the god's favor, Christians would have no doubt created a buzz disproportionate to their numbers (easy to find modern parallels), so it didn't need to have had an especially large membership in Rome at that time to have already attracted the mob's attention and for Nero to have played to them.

Ben

[David Atherton]

I was wondering how Stark came up with the 40% per decade growth rate...thanks for the explaination Ben.

The figures actually make sense in terms of the history we know from the time and what I always had an idea they would be. A most enlightening set of stats.

This book is indeed on my 'to buy list'.

[Robert_Brenchley]

Christians wouldn't necessarily have made any sort of stir rejecting the state religion this early, as Jews did exactly the same, and it was essentially a Jewish sect. The problem was that here was a small splinter group within a minor Jewish sect which wasn't made up of 'proper' Jews at all; a significant number of them had rejected all the accepted Jewish markers; circumcision, Sabbath observance, and so on. So what were they? Any minority is always vulnerable, and it wasn't so long before that Claudius exiled Rome's Jewish population. They moved back in, taking advantage of Nero's more liberal regime, but they must have ben even more vulnerable than before. Then came the fire, and someone said 'Look, it's that bunch of fake Jews'. I am, of course, assuming that the 'Christiani' were indeed Pauline Christians; the term could equally well refer to messianic Jews.

[gavignano]

I am not a scholar, but, is the idea that the "proper" Jews turned on, in a politically sophiticated way, the "improper" Jews (that is, the Christians who were "converts" from Judiasm) likely in Rome, or would such a thing have been more likely in the Jerusalem area?
Were not many of the people who embraced Christianity in Rome proper the Gentiles?

[Robert_Brenchley]

Of course. The church in Rome was probably founded by observant Jews, since it wasn't founded by Paul. Claudius expelled the Jews, but it survived, probbly run by Gentile converts. By the time he wrote his letter, Jews were moving back in, and there were tensions within the church over Sabbath observance and kosher food. But it was still essentially a Jewish movement, worshipping the Jewish god. Despite Paul's splinter group, the vast majority overall were observant Jews.

How open a Jew was to Gentiles depended how strict they were. At one end of the spectrum we have people who regarded other Jews as belonging to 'the lot of Satan'. Their views on the acceptability of Gentiles to God aren't recorded that I know of, but we can certainly guess. At the other end of the scale, more liberal Jewsbeleived that God would accept Gentiles if they accepted a few basic commandments; no murder or fornication, no meat with blood in, no idolatry, and so on. There's a very similar position taken in Acts. But they were still Gentiles. Paul had blurred the distinction to the point where people didn't know how to relate to his churches; which people did they really belong to? The situation seems to have made Jews feel really insecure, hence the reaction. Acts may exaggerate a bit; Luke makes the Jews the villains every time, while butter never melts in a Roman's mouth. But there's enough evidence in Paul of major tensions.

[gallienus1]

I’ve been following this thread with great interest. I agree with Ben that the Christian rejection of the repulsive pagan practice of infanticide and their care for their own sick would have been factors in the increase of the Christian population. But that does not seem to me to fully account for what was apparently the boom in Christian numbers between the “Edict of Toleration” in AD 311 by Constantine, and the burning of the Sibylline Oracles in AD 407. The reason for it was the persecution of Pagans. The Christians once in power, quickly became violent towards pagans, temples were burned, pagans attacked in the street (the murder of Hypatia by a Christian mob is a famous example) and the following of pagan ritual punishable by law. We KNOW this took place. The early Christian writers tell us.

Steve