By Bart D. Ehrman, The University of North Carolina, Chapel Hill
The triumph of Christianity in the Roman world is a much debatable topic, owing to the lack of reliable sources. However, the one thing that is discernible in this regard is a steady rate of growth. The first scholar to recognize this was the sociologist of religion, Rodney Stark, who discussed this theory in his controversial book The Rise of Christianity.
How Fast Did Christianity Spread?
If we take a look at the ancient literary sources, they suggest that Christianity spread like a fire—from 20 people to two to three million people in 300 years. Some have argued that it would require a divine miracle. But, looking at this on theological grounds, if the growth of Christianity were accomplished by God, why did it take so long and why was the job never finished?
Other people argue that it requires massive conversions at one time. If you go from 20 people to three million, you must have thousands of people abandoning their pagan ways to become Christian at one time, at the ancient equivalent of Billy Graham’s evangelistic crusades.
Rodney Stark’s Beliefs on Christianity
As it turns out, neither option is right. All that is required is a steady rate of growth.
The first scholar to recognize this was the sociologist of religion, Rodney Stark, who set this forth in his controversial book The Rise of Christianity.
Stark begins by assuming that the book of Acts exaggerates a bit on how many Jews converted within the first weeks, months, and years of the movement. And he suggests that we simply start in the year 40 CE, a decade after Jesus’s death, with 1,000 Christians in the world. Stark ends with the standard number of five to six million Christians by 300 CE.
This article comes directly from content in the video series The Triumph of Christianity. Watch it now, on Wondrium.
Analyzing Stark’s Theory
How fast does the church have to expand to go from 1,000 in 40 CE, to five or six million, just 260 years later? It requires a completely believable and achievable rate of growth of about 40% per decade.
That is, if there are 100 Christians this year, in 10 years they need to grow to 140. That means basically every year the 100 Christians among them as a group need to convert three or four people. If every 100 Christians do that, year after year, after 260 years, they have grown from 1,000 people to five or six million.
Exponential Curve
In a way, it’s like the spread of disease. If one person with a virus infects, on average, two others, and each of them on average does the same, before long you have a worldwide pandemic on your hands.
That’s because the rate of growth involves an exponential curve. The rate remains the same, but as soon as there are more and more infected people, or more toward our immediate interest, more Christians, the numbers grow hugely over time.
Using an Analogy
To understand it better, think about investments. If you have $100, and you make 7% on your money, it’s nice that next year you’ll have $107. But it’s not a lot more than you started with. But if you make the same 7% on $1 million, you’ll add $70,000 to your investment. And at the same rate of growth more the next year, year after year.
With conversions, of course, the rates would not be steady, 40% every decade. They would fluctuate depending on all sorts of issues, including birth rates, death rates, problems with epidemics, and natural disasters, not to mention the effect of major persecutions on the attractiveness of the religion to converts and so on.
So, this rate is an average over several centuries, and sociologists have to take a variety of factors into account.
Stark’s Observations on the Growth Rate
The key thing to notice is that there is nothing miraculous about this rate of growth for the early Christians. Stark notes that, in fact, the Mormon Church from the time of its beginning to the time of his writing in 1996 had grown at just about the same rate—43% per decade.
It’s worth noting that the vast bulk of the growth among the Mormons is not by door-to-door evangelism, as one might think. Most of the conversions happen when friends, and neighbors, convert friends and neighbors.
Finding Logic in Stark’s Theory
In the ancient world, the male head of the household, the paterfamilias, determined the religion of the house. If a man was married with two children and if he converted to the Christian faith, he would make his family also accept the new religion.
With one convert, there are another four. One might object that these other three aren’t really Christian since they’re being forced into it. But even if they do have qualms, they are practicing Christianity rather than some other religion. And so demographically they count.
Moreover, if they spend the rest of their lives following this religion, they almost certainly, over time, are going to start finding this faith acceptable, and even desirable and begin to commit to it themselves. The family for generations to come is then Christian.
With this explanation, the beliefs put forth by Stark seem acceptable and logical.
Common Questions about Sociologist Rodney Stark’s View on the Triumph of Christianity
Rodney Stark begins by assuming that the book of Acts exaggerates a bit on how many Jews converted within the first weeks, months, and years of the movement. And he suggests that we simply start in the year 40 CE, a decade after Jesus’s death, with 1,000 Christians in the world. Stark ends with the standard number of five to six million Christians by 300 CE.
Rodney Stark proposed that the church has to expand to go from 1,000 in 40 CE, to five or six million, just 260 years later. It requires a completely believable and achievable rate of growth of about 40% per decade.
The key thing to notice in Rodney Stark‘s numbers is that there is nothing miraculous about his proposed rate of growth for the early Christians. Stark notes that in fact, the Mormon Church from the time of its beginning to the time of his writing in 1996 had grown at just about the same rate, 43% per decade.
