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How Many Christians Does it Take . ..?

March 27, 2017

How do historians estimate the number of Christians in the earliest centuries?  In a previous posting I commended Thomas Robinson’s new book here, in which he shows how the numbers often used by historians don’t “add up.”  But a comment asking how historians arrive at their estimates prompted me to this posting.

I think that one factor is Constantine’s adoption of Christianity in the early 4th century.  The implicit or explicit assumption is that for him to have seen this an advantageous action Christianity must have been fairly successful already.  It is often assumed that a growth comprising perhaps 10% of the population would have been necessary for Christianity to have attained such credibility for Constantine to have adopted it.

Now it is also necessary to estimate the population of the Roman Empire, and estimates vary widely, but something close to 60 million is frequently cited.  So, 10% Christians would = about 6 million Christians by about 300 AD.

In short, this is all very rough and ready estimates or scholarly guesswork.  (But it’s scholarly guesswork!)

A recent comment posed a good additional question:  How many Jesus-followers were there at the outset, in the earliest years after Jesus’ crucifixion?  One could infer from the Gospel accounts that Jesus had aroused a certain number of followers during his ministry, perhaps especially in Galilee.  These would be additional to the more well-known group of followers who seem to have (re)located to Jerusalem.

From Paul’s reports of his own early efforts to “destroy” (his word) the young Jesus-movement, one could infer that, already within the first year or two, it had become highly visible, and generated the rather harsh verdict reflected in his efforts.  Perhaps, as well, the Jesus-movement had already begun to grow impressively, and this, too, was a factor that generated the concern of this then-young Pharisee.

From a very early point, also, the Jesus-movement was trans-local, with followers mentioned in Damascus and Antioch, and probably other places as well.  So, it is possible that what became “Christianity” was, from a very early point, a rapidly spreading movement.  But it appears that across the second and third centuries this growth continued, with impressive cumulative numbers.

Tertullian (ca. 200 AD) claimed an “immense number of Christians . . . almost all the inhabitants of your various cities being followers of Christ” (Apology 37), and that “our numbers are so great–constituting all but the majority in every city . . .” (To Scapula 2), and that pagan critics “groan over the increasing number of the Christians” (Ad Nationes 1).  This may well be deliberate exaggeration for rhetorical effect.  But it would have been somewhat counter-productive to make such claims if the number of Christians had been totally insignificant.  So, I think that it is likely that, at least in some areas (such as North Africa, where Tertullian lived), Christians were sufficiently numerous to be rather highly visible and of concern to pagan opponents.

Why people joined the Christian movement in this period, given the social costs involved, is the question I urge that scholars should consider more closely in my recent book:  Why on Earth did Anyone Become a Christian in the First Three Centuries? (Marquette University Press, 2016).

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  1. Marc permalink

    I see a lot of speculation and no hard data here. What does the archaeology say, for instance? Is there any scholarship quantifying the number of artifacts, extent of ruins, etc and analyzing their quality and character and geographic distribution? It seems to me this would be a more rigorous way to estimate Christianity’s reach compared to other religions and movements of the time than guesswork, no matter how scholarly, based simply on ancient writers’ subjective views and Constantine’s conversion. 2 data points do not an historical theory make.


    • Well, first, Marc, Constanine’s approval and then adoption of Christianity is “hard data”, and requires some reasonable explanation. Second, the main artefacts of Christianity in the first three centuries are an impressive body of texts that report on various things, including the presence of Christians in various places, all across the Mediterranean. As I note in my recent book (Destroyer of the gods), Christians didn’t then construct a lot of shrines, steles, altars, or a lot of art, the sorts of things you want. They were a different kind of movement in which beliefs mattered more. Second, as I and others noted, any specific figures are so much guesswork. But, again, some likely success of Christianity seems necessary to help explain Constantine’s move.

      • Marc permalink

        Dr. Hurtado — If you limit yourself to the manuscript data, what is the percentage breakdown of Christian, Jewish, Egyptian, Greek, Persian, etc, and mixed religious texts during the period? Has that work been done? I think that would give you some idea of Christianity’s reach in the population (although probably a maximum since you’ve found Christians to be especially bookish).


      • These data are best available via the Leuven Dababase of Ancient Books:
        But the extant copies of texts won’t readily tell you the comparative percentage of Christians or Jews, for example, to the general population.

      • Marc permalink

        Thank you Dr. Hurtado. What a great resource! Here is the data.

        Number and Percent of Books (LDAB) by Religion and Century, 1 AD – 200 AD
        1st Century 2nd Century
        Total 2,843 100% 4,483 100%
        Secular 275 10% 450 10%
        Christian 0 0% 125 3%
        Classical 2,100 74% 3,625 81%
        Classical/Egyptian 150 5% 200 4%
        Egyptian 50 2% 50 1%
        Jewish 275 10% 25 1%

      • Marc: Your layout is rather hard to read, but it’s basically clear. I’m not sure what you mean by “secular”. By the way, you can also produce pie charts and bar graphs from the LDAB site (but you have to study the directions carefully to do so.)

  2. Considering there were so many prominent Christian writers in the second century Roman Empire that are preserved until today, even in fragments (Irenaeus, Tertullian, Justin Martyr, Shepherd of Hermas, Papias, etc, and a massive ton of apocryphal works), it should imply that there were a rather large amount of Christians. I think Christianity passed 100,000 followers by the end of the second century.

  3. There is nothing in the ancient evidence or in modern techniques that would allow us to specify the number of Christians in the Roman Empire. I think we are simply left with our impressions, and impressions vary widely from scholar to scholar. The 10% figure so often touted is purely a guess. We know that Christians came to the notice of authorities and something their presence (and sometimes specifically their size, as with Pliny’s action) provoked governmental (and sometimes mob) response. Christian writers who addressed the matter generally emphasized the size or spread of the Christian movement, but with rhetorical twists that leave me somewhat wary, though not entirely dismissive. My concern in “Who Were the First Christians? Dismantling the Urban Thesis” is to show that there could not have been even a 10% Christian population in the empire without a large contingent of rural Christians. (1) If Christianity is largely urban, then all urban areas would have been saturated with Christians, leaving no room for Jews or pagans. (2) If we place half the Christian population in the countryside, we still have all urban areas half filled with Christians (which seems unlikely, and which would collapse the urban thesis). (3) Since more (most) Christians were in the eastern empire at this time, that would place even more Christians in the countryside, for we have fewer urban areas to house our 10% Christian population.
    Regarding urban areas, the percentage of Christians would have varied substantially from place to place. Some areas look heavily Christianized by the time of Constantine (areas of Phrygia, for one), and Alexandria strikes me as well on its way to a considerable Christian population. But these are impressions, and I don’t know how we can say with any confidence that a city had 15% rather than, say, 40%. I recommend caution about numbers. And, of course, I recommend a rejection or thorough revision of the urban thesis.
    As for how Constantine would have seen the situation, he lived for years in the imperial capital of Nicomedia, as close to an area of successful Christian mission as one might find; he was there when the Great Persecution was ordered, and when a Christian church within sight of the imperial palace was destroyed. Only in mid-305 did he go to meet his father in the west. In the west he would have had another kind of impression, an empire largely devoid of Christians, for most Christians at that time lived in the eastern part of the empire (one of the good guesses we can make). How any of this affected Constantine cannot be determined.

  4. John Mitrosky permalink

    Larry I wonder what your educated guess might be about the number of Christians per decade, up to the end of the first century? 30’s? 40’s? 50’s? 60’s? 70’s? 80’s? and 90’s? Thanks.

  5. Peter Bylen permalink

    If churches were headed by Bishops, if each church had roughly 100 households (with estimated 4-to-6 persons per household), and if Constantine had invited all 1,800 bishops of the Christian church within the Roman Empire (although only 318 attended) there would be 720,000 to 1,080,000 professing Christians at the time.

    • But by the time of Constantine, “bishops” were often “metropolitan” in coverage, with several churches under their responsibility.

  6. Dr. Hurtado, it is my understanding that the very first Christians were all Jewish. This would have been prior to Paul becoming the Apostle to the nations. In your opinion, at what point did the number of non-Jewish Jesus believers exceed Jewish Jesus believers, and when did the number of Jewish Jesus believers decline to zero (and I ask all this realizing you might not have an answer)?

    • I don’t know that anyone can say with sound basis when the balance of gentile to Jewish believers tipped. A safe claim would be that this had happened by the end of the first century. But Jewish believers never seem to have disappeared altogether.

  7. GPG permalink

    Often people will follow a leader, or a movement, even when it seems counterproductive over the short term.

    The early Marxists and Leninists for example, followed their ideas. Even though in the early days many were jailed, and then killed.

    In part they persisted because they believed their cause would triumph over the longer term.


    • OK. But the first three centuries aren’t “short term”! Indeed, opposition grew more concerted, at least in some places, across this period. And the growth seems to have been socially vertical as well as in numbers. In contrast with the early Marxists & Leninists, the early Christian movement wasn’t seeking a political revolution. They were willing to support the political regime (emperor, etc.), and only sought not to be punished for being Christians.

      • GPG permalink

        Well, the whole time scale was lengthened by Christians. When Christians were trained to think of rewards after death. Or even in eternity.

        That made them more tolerant of persecutions, even for their whole lives. And then, generations.

        The tolerance for a deferred reward was extended especially when Revelation spoke of rewards to come in thousands of years. Including not just an end to persecution. But also a positive kingdom.

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