By Bart D. Ehrman, The University of North Carolina, Chapel Hill
Based on ancient literary sources and other pieces of evidence, it is believed that Christianity saw a rapid spread in the early years. The numbers are believed to go up from approximately 20 people to two to three million people in 300 years. Although it is difficult to pin down a particular number, the figures can be crunched and analyzed to discern a patterned growth rate.
Growth Rate in the Early Years
Sticking to the suggested numbers—20 people in the year 30, and two to three million people by 300 CE—it is understood that the rates of growth will almost certainly be higher at the beginning of the Christian movement when the enthusiasm for the movement generated heightened energy for evangelism.
This can be deduced since, in the 50s, Paul writes to a lot of churches whose numerous problems suggest that they comprise more than four or five people each. And so, there’s proof that early on there was increased evangelism.
Average Growth Rate
Moreover, the rates absolutely had to slow down near the end of the period. If a 40% rate of growth had been sustained after 300 CE, by 400, there would have been more Christians in the Roman Empire than people.
And so, they have to go faster at the beginning, and slower at the end. Once the numbers are adjusted in a sensible way, it appears that the growth rate, even if varying, averaged about 35% over the entire stretch of time.
So, how many Christians were there at any given time? For example, when Paul wrote his letters, were there 100 Christians then, or were there 10,000? Or how many were there in the year 100? How many say 200 years after the death of Jesus?
We may have some kind of rough ideas in our heads when we think about it, but these ideas probably come just from our general sense of things, possibly based on old movies like Ben-Hur or Quo Vadis or rather sensationalist documentaries on the apostles or the spread of Christianity.
This article comes directly from content in the video series The Triumph of Christianity. Watch it now, on Wondrium.
Approximate Number of Converts
Since there is no reliable source, we can only have approximations. In the year 30, we’re starting with 20 Christians right after Jesus’s death. By the year 60, we are near the end of Paul’s ministry. So, if we follow the statistics as per 40% growth rate, we can say there were some 1,000 to 1,500 Christians.
By the year 100, the end of the 1st century, there would be between 7,000 and 10,000 Christians in the world. It is noteworthy that this is out of the population of the empire, just the empire of 60 million; seven to 10,000 out of 60 million.
By the year 150, there would be between 30,000 and 40,000 Christians. By the year 200, there would be between 140,000 and 160,000 Christians out of an empire of 60 million.
By 250 CE, the time of the first imperial persecutions, there would be between 600,000 and 700,000 Christians. And so, you can see the curve is starting to go up rather significantly.
By 300 CE, the time when Christians were seriously being persecuted there would be between 2.5 and 3.5 million Christians. And by the time Constantine converted to Christianity, there’d be between 3.5 and 4 million Christians. By the end of the century around 400 CE, there’d be roughly 25 million or 35 million Christians at this rate of growth.
Evangelistic Techniques
The number of Christians at any given period in time refutes the claims of the literary sources. This is largely debatable, since there are not many surviving Christian writings telling us what was actually happening in the early Christian centuries.
The one thing to note here is the evangelistic approach that was being taken up to achieve this rapid spread.
First, there’s no reason to think this rate of growth is being achieved by massive missionary campaigns. In fact, in the 260 years between Paul and Constantine, there basically was no organized missionary work at all.
Only three missionaries working at the time are heard of: Gregory the Wonderworker, from the 3rd century; Martin of Tours from the 4th century in France; and the 4th century Bishop Porphyry in Gaza. So the religion was circulating not through missionaries, but through social networks.
The Role of Networks and Connections
Christians, like everyone else, had connections. Connections with their family, neighbors, the town and organizations they belonged to, and the like.
People in the ancient world talked about religion. Christians would discuss religion with the various people in their various networks and they would convert some people.
It was all happening by word of mouth. A woman converts her neighbor who converts her spouse, who converts his cousin, who converts his business associate. And so it goes.
This was especially feasible in urban areas where population density was extreme.
Common Questions about the Spread of Christianity
Considering the increase in numbers until 300 CE, a growth rate of 40% is discernible. But, if a 40% rate of growth had been sustained after 300 CE, by 400, there would have been more Christians in the empire than people. And so, they have to go faster at the beginning, and slower at the end. Once the numbers are adjusted in a sensible way, it appears that the growth rate, even if varying, averaged about 35% over the entire stretch of time.
The religion was circulating not through missionaries, but through social networks. People in the ancient world talked about religion. Christians would discuss religion with the various people in their networks and they would convert some people.
The number of Christians at any given period in time refutes the claims of the literary sources. This is largely debatable since there are not many surviving Christian writings telling us what was actually happening in the early Christian centuries.
