According to Rodney Stark the movement that Jesus founded numbered about 1,000 by AD 40. By AD 300 it has grown to somewhere between 5-7.5 million. So when we consider the rise of Christianity there is really only one question that needs to be addressed: How was it done? How did a tiny obscure messianic movement from the edge of the Roman Empire dislodge classical paganism and become the dominant faith of Western civilization? By the end of John Wesley's lifetime one in 30 English men and women had become Methodists. In 1776 less than 2 percent of Americans were Methodists. By 1850, the movement claimed the allegiance of 34 percent of the population. How was it done? The twentieth century has seen rise of Pentecostalism as possibly the most rapidly growing missionary movement in the history of the Church. The movement has grown from humble beginnings in the early 1900s to 400 million by the end of the twentieth century. It is estimated by 2050 Pentecostalism will have one billion adherents worldwide. How was it done? At the heart of the answer to this question is the reality that faith is both socially transmitted and socially maintained. Without this social dynamic in play, exponential growth could not be initiated or sustained.
Pre-existing relationships are the key to any exponential growth of a movement. New religious movements fail when they become closed or semi-closed networks. For continued exponential growth, a movement must maintain open relationships with outsiders. They must reach out into new, adjacent social networks. Stark argues as movements grow, their â"social surface" expands exponentially. Each new member opens up new networks of relationships between the movement and potential members ”provided the movement continues to remain an open system. The forms of social networks will differ from culture to culture but, â€œHowever people constitute structures of direct interpersonal attachments, those structures will define the lines through which conversion will most readily proceed."
That's why contagious relationships are at the heart of the spread of every dynamic movement. That's how God uses ordinary people to change the world. The Rise of Christianity: How the Obscure, Marginal, Jesus Movement Became the Dominant Religious Force ....(Rodney Stark)