“In A.D 30, seven weeks after the death and resurrection of Jesus, 120 men and women gathered in Jerusalem to wait and pray for the promised Holy Spirit. That day, the movement that Jesus founded was numbered in the hundreds. By the end of the day, it was thousands. By A.D. 66 there were around 40,000 followers throughout the Empire. By the end of the first century that number had grown to 100,000. By A.D. 300 the number had grown to around 6 million people, or about 10% of the population of the Roman Empire….
Never has any movement- social, religious or political- achieved such a rapid advance in a dominant culture without the aid of military force….How was it done? Early Christianity was not spread by “professionals” but by ordinary people whose names and deeds went unrecorded. The Roman authorities sought to halt the expansion of Christianity by targeting its leadership….This did not work, however, because early Christianity was a mass movement with a highly committed rank and file who were spreading the faith. Christian conversions followed a network of relationships.”
– Movements that Change the World, p.73-74.