The Triumph of Christianity

by Bart D. Ehrman

  THE NATURE OF OUR DATA

  It is difficult to know exactly how quickly Christianity grew because we have very few hard data. But we have some. One particularly important statement appears to be a disinterested record of fact concerning the situation of the church in the city of Rome in the middle of the third century. The statement comes in a letter by the bishop of the church, Cornelius, in which he provides some much-welcome hard numbers: the church of Rome, he informs us, had at the time 46 presbyters, 7 deacons, 4 sub-deacons, 42 acolytes, 52 exorcists, readers, and doorkeepers, and 1,500 widows and other needy persons under church support (Eusebius, Church History 6.43).

  This is a significant data point. The great historian of early Christianity Adolf von Harnack claims: “So far as regards statistics, this passage is the most important in our possession for the church history of the first three centuries.”5 In a city of around a million people, the church had 155 clergy (counting the bishop himself) and provided charitable support to 1,500 people. The 46 presbyters would each have had charge of a smaller community that met for worship, so that at the time there would have been that number of actual churches (gatherings, not necessarily buildings) in the city. On the basis of these data, Harnack surmises that the church in Rome totaled approximately 30,000 persons.

  In a footnote, however, he acknowledges this figure might be too low. We know from the fourth-century bishop of Constantinople, John Chrysostom, that his own church of 100,000 provided material support to some 3,000 needy persons—that is, to about 3 percent of the total. If a comparable rate applied to the church of Rome some decades earlier, the church may have numbered something like 50,000. If that is a closer approximation, the church would have comprised about 5 percent of the population of the city.

  In his exhaustive treatment, Harnack cites and analyzes every reference to Christianity and Christian churches in every surviving text of the first three centuries. As just one other example, he notes that in the same letter Cornelius mentions a regional synod of church officials attended by sixty bishops from Italy. From this reference Harnack surmises (on grounds he elucidates) that there were probably about a hundred bishops altogether in the region in the mid-third century—meaning about a hundred churches just in Italy.

  On the basis of his survey, Harnack comes to some significant statistical conclusions, the most frequently cited of which is one with which we are by now familiar: by the beginning of the fourth century, probably 7 to 10 percent of the empire was Christian. As one contemporary expert, Harold Drake, indicates: “Almost everyone is willing to admit that this number feels about right.”6 If it is indeed right, and the population of the empire was approximately 60 million, then Christians would have numbered somewhere between 4 million and 6 million, most of them located in the eastern provinces.

  There are some reasons for suspecting, however, that the number may be on the high side. One of the most startling and disturbing recent analyses has been provided by Yale historian Ramsay MacMullen. The study is predicated on the fact that, after his conversion, Constantine sponsored the building of numerous churches both in Rome and throughout the empire. Moreover, as Christians came out of the woodwork and large numbers of wealthy people began to convert, numerous other churches were built. MacMullen’s study tries to determine how many individuals these churches could accommodate during a weekly worship service, based on the actual size of the building and the space required for the human body. This is a novel approach to determining how many Christians there were, or at least how many Christians there were who would have been worshiping in the church structures at the time.7

  The numbers are shocking. MacMullen shows that “out of some 255 churches in some 155 towns and cities, wherever the remains survive for the record, the expected attendance ranged between a mere 1 per cent and 8 per cent of the general population.”8 This is not in the second or third centuries, when Christianity was known to make up a small fragment of the overall population. It is the fourth century, when the church is widely thought to have been taking over the world. Why is there not more room for worship?

  MacMullen points out that in a typical fourth-century city of 20,000 persons, there was, so far as we can tell, an average of only one church that could, with rare exception, accommodate only 350 to 400 people (2 percent or less of the population). Moreover, he stresses that the church sizes were not restricted by limited funds. On the contrary, funding was abundant. Churches were built to accommodate the numbers of worshipers who could be expected to attend.

  These findings based on archaeology are hard to explain, even for MacMullen. Given what we know from our literary sources, they simply cannot mean that the church was not growing at all. It was demonstrably growing, and there are other explanations for the size of the actual church buildings. Possibly most Christians simply did not go to church every week. Or ever. Possibly they continued to meet more often in homes, attending the one church building in town on only rare occasions. Possibly Christians preferred to meet in outdoor spaces. We do know that Christians often gathered together in cemeteries. Were these their primary meeting places? Did most Christians not see a need to meet together much at all? The reality is that we simply cannot know.

  But MacMullen’s surprising findings may suggest that Harnack’s conclusions, based on an analysis of strictly literary sources, may be a bit too sanguine. Possibly 7 to 10 percent of the empire by the year 300 is an overestimate.

  Pointing in the same direction is the fact, too infrequently considered, that in its first three centuries Christianity succeeded principally in urban settings, but the bulk of the population was rural—by a typical calculation, probably 80 to 90 percent of the empire. These countryside masses were by and large not converted until the fourth century, and even then rather slowly. This makes it even more difficult to determine how much of the total population, urban and rural, was Christian by the year 300. It seems altogether unlikely, based on both the literary and material evidence, that it could be as high as the 10 to 20 percent range. If Harnack’s numbers may overreach, possibly it is most reasonable simply to halve his figure and think generally of something like 2 to 3 million Christians in the year 300. Possibly it was slightly less. As we will see in a moment, given the rate of Christian growth, surprisingly enough, the exact number does not matter much.

  THE DEMOGRAPHICS OF CONVERSION

  First, it is important to consider several matters of demographics. The vast bulk of the ancient population comprised lower classes. The very upper crust of the aristocracy—the senators of Rome, the next level down known as the equestrians, and the local elite of cities throughout the empire called decurions—altogether made up just over 1 percent of the total population. With respect to the other 99 percent, there was not much of a middle class to speak of in Rome’s noncapitalist, preindustrial society. There were, to be sure, large differences in wealth, even in a world where the great majority of people were living on the economic edge. But the majority of people did live on that edge, including most of the people coming into the Christian faith. Pagan intellectuals such as Celsus may have mocked Christians for being attractive principally to the poor and uneducated, but the reality is that this was most of the population.

  For reasons I have already explained, it proved much easier to convert people in urban settings than in rural ones. The urban centers were packed with people. Rome itself had a population of nearly two hundred persons per acre, and the number on the ground was much higher than that, since about a quarter of the city was public space without housing. Such dense populations made human interchange much more frequent than in rural settings. As MacMullen points out, “the narrower one’s house, the more time would naturally be spent among one’s neighbors, the more intercourse and friendliness, the more gossip and exchange of news and sense of fraternity.”9 And, accordingly, the more opportunities for conversion, as information about this new cult could spread like wildfire, no less quickly than rumor and gossip.

  It is c
lear that Christianity grew at different rates in different cities and regions. Both literary and archaeological sources confirm there were far more converts in the East than the West in the first three hundred years; it was not until the end of the second century that western provinces began to be seriously Christianized at all. Rome itself was an obvious exception. Moreover, some parts of the East—for example, Asia Minor—saw Christian growth much more quickly than others.

  Egypt is a good example. One of the fascinating studies of the Christianization of Egypt was undertaken by a Roger Bagnall, at the time a professor of ancient history at Columbia.10 Bagnall applied an interesting method for determining how quickly Egypt became Christianized. It had to do with a field called “onomastics,” the study of personal names. As Christianity spread throughout the empire, Christians started giving their children Christian names. As an obvious example, Peter was not a name at all in antiquity before Christians arrived on the scene. The name Peter is based on a nickname given to one of Jesus’s disciples, Simon son of Jonah (John 1:42). It is a word that means rock. We are not sure why Jesus wanted to call Simon “the Rock,” but he did, and years afterward Christians would sometimes give their children the name of this famous disciple. Non-Christians had no inclination to do so.

  Some names are thus definitely Christian, and if enough documents survive from any region—such as tax records, marriage certificates, and land deeds—it is possible to determine what people are named at different periods of time and on that basis to calculate how many of those people were Christian (based, at least, on the naming practices).

  As it turns out, we see very few traces of Christianity in Egypt before the middle of the third century, unlike, say, the city of Rome, which had a large church already in Paul’s day. For most of the time prior to the conversion of Constantine, Egypt was almost entirely pagan. It was not completely so, as we know of some Christians and Christian literary activity there, especially in Alexandria. But Christians were hugely outnumbered by pagans until the end of the third century.

  Then there was a striking shift. On the basis of his initial analysis, Bagnall argued that Christians had become half of the population sometime between 318 and 330 CE; 75 percent of the population by the middle of the fourth century; and 90 percent by the end of the century. These results, he maintained, can be confirmed from other evidence: records in our surviving papyri, inscriptions, and literary sources such as the hagiographic tales of the Egyptian saints.11

  Thus, the growth of Christianity in Egypt did not parallel the situation in Rome, or Antioch, or Jerusalem. Each place was different. This idea that Christianization was wildly uneven throughout the empire is not new or controversial. Already Harnack had differentiated rates of growth, as he identified some places where, by the year 312 CE, Christianity was nearly half the population (for example, Asia Minor, Armenia, Cyprus); where it was less than half but very strong (Antioch, parts of Egypt, parts of Italy, Spain); where it was very sparse (Palestine, Phoenicia, Arabia); and where it hardly existed at all (upper Italy, middle and upper Gaul, Germany).12

  These basic findings have been confirmed by further analyses in recent times, as cited, for example, by Frank Trombley, a leading expert on the Christianization of the empire, who not only reconsidered all of the literary evidence adduced by Harnack but examined scattered inscriptions, remains of papyri, and archaeological findings. These kinds of evidence allow us to speak more authoritatively about the presence of Christianity in specific cities, towns, and rural areas. Trombley noted that the newer evidence tends to support the findings of Harnack but also provides some important nuance. Among other things it appears that major cities serving as capitals of provinces—places such as Rome, Antioch, and Thessalonica—did not become predominantly Christian until the middle of the fourth century; fairly large regional towns in the provinces at the time were often roughly balanced between pagans and Christians then. But many places, such as Athens, Delphi, and Gaza, remained predominantly pagan, even into the early fifth century.13 The growth of Christianity, in short, was uneven. People converted in different numbers in different times and places.

  THE RATE OF CHRISTIAN GROWTH

  Still, it may be possible to calculate some very rough sense of the rate of Christian growth over the first few centuries. That will require a bit of number crunching, and there is no one better at crunching numbers than a sociologist. It was indeed a sociologist, Rodney Stark, a specialist in modern religious movements, who made the first serious attempt at establishing Christian growth rates in the first several centuries in his popular book The Rise of Christianity.14

  Because the discussion of Stark’s analysis requires statistical computations—not the most scintillating of reading—I have relegated it to the appendix, beginning on page 287. Suffice it to say here that Stark’s numbers need to be nuanced for a variety of reasons, even if his overall thesis appears to be rock-solid: the triumph of Christianity over the pagan religions of Rome did not require a miracle from on high. It required a steady growth in the church, one convert after the other, year after year, for the first three centuries.

  Once Stark’s numbers are appropriately tweaked, it is clear that Christianity was growing only at a rate—very roughly—of 30 percent or so per decade for the majority of this period. In other words, if there are a hundred Christians this year, there need to be another thirty or so ten years from now. The results of the calculations explained in the appendix can be cited here. The following gives a rough estimate of the number of Christians at key moments of the movement, starting right at its beginning immediately after Jesus’s death:

  30 CE—20 Christians

  60 CE—1,000–1,500 Christians

  100 CE—7,000–10,000 Christians

  150 CE—30,000– 40,000 Christians

  200 CE—140,000–170,000 Christians

  250 CE—600,000–700,000 Christians

  300 CE—2.5 million–3.5 million Christians

  312 CE—3.5 million– 4 million Christians

  400 CE—25 million–35 million Christians

  To non-statisticians, these raw numbers—especially toward the end of the chart—may look incredible. But in fact they are simply the result of an exponential curve. If 25,000 to 30,000 Christians were added in the half century between 100 and 150 CE, then at the very same rate of growth, during the half century between 250 and 300 CE, something like 2 million or 2.5 million Christians would be added.

  The enormous numbers provided by a steady rate of growth can be seen especially at the end of the graph. If there were just 2.5 million to 3.5 million Christians in the year 300, the church would have to grow only at a rate of 26 percent to reach 30 million by the year 400.

  The nature of this exponential curve can be seen in the following tables:

  I need to stress that we are not talking about implausible rates of growth, even though the numbers at the end of the period are staggering. For the fourth century, if the rate really was around 25 percent per decade, that would only mean that every hundred Christians would need to convert just two or occasionally three people a year.

  In that regard, it is important to remember that conversions include everyone who begins to adopt Christian practices. If the head of a household converts, and he brings his wife and three children into the fold so that they too adopt the new faith, then you have five new members.

  We know these kinds of “family conversions” occurred from the very beginning of the Christian movement. They are recounted in the book of Acts as a matter of course as if there was nothing at all unusual about members of a household joining the paterfamilias (or even the materfamilias) in the faith. And so, when Paul and his companions are in Philippi, they convert a wealthy woman named Lydia, and immediately “she and her household were baptized” (Acts 16:14–15). Soon thereafter an unnamed jailer learns he must believe in Jesus to be saved, and “he and his entire family were baptized without delay” (Acts 16:33). I am not saying these accounts are
necessarily historical. But the author of Acts saw nothing at all unusual in an entire family joining in the new faith of the head of the household.

  It would thus be a relatively simple matter for the church to grow at a rate of 2.5 percent per year—the rough rate of growth we are hypothesizing for the fourth century. It would simply mean that every group of a hundred Christians would have to witness one male adult convert, along with his small family, every two years. That would make the church grow from 3 million to about 30 million in just the fourth century. The rate of growth does not have to be vastly different if at the beginning of the century there were only 2 million Christians (just under 3 percent a year).

  SOME IMPLICATIONS

  In a discussion of Christian growth in the first four centuries, Roman historian Keith Hopkins drew out some intriguing implications of the numbers of conversions that had been discussed by Stark. I have tried to provide some nuance for these numbers while allowing broader figures, but for the most part they are not radically different from Stark’s, and many of the implications are very much the same.15

  I have already discussed the exaggerated claims of various ancient sources. We can now consider these in light of more sensible estimates. Clearly the book of Acts cannot be right that within two months or so of Jesus’s death there were some 10,000 Christians in Jerusalem; nor can Tertullian be right that around 200 CE the majority of people in the empire were Christian. Not even close.