Christianity’s rise as a creator of culture was rapid. Within 50 years of the crucifixion of Jesus, the church had gone from a rural religion from a backwater of the Roman Empire to a religion that vied for acceptance among the most powerful cities of the time. This was so much the case that those who were outside the church became classified as the “pagans,” a term derived from pagus meaning a rustic or country person. Christianity, in such a short time, had become the religion of the civilized masses.
Luke’s account in Acts 2 of the mass conversion at Pentecost was not the norm for the fledgling church. Rather, the church grew and gained influence through a slow process of cultural accretion. Rodney Stark examines this growth through slow cultural influence in his book Cities of God: The Real Story of How Christianity Became an Urban Movement and Conquered Rome. His conclusion is that Christianity did not require a large number of converts to overtake the Roman Empire as quickly as it did. He projects that the total number of converts within the Roman Empire by A.D. 350 would have been at 31,722,489 people from a starting group of only 1,000 in A.D. 30 with only a 3.4% increase in conversion per year (Stark, 67)
Stark tracks the church’s growth through a collection of cultural factors that influenced how it spread. First, the early missionaries tended to use the major sea routes to travel and stuck to evangelizing within the major metropolitan areas that connected these routes. This was a practical strategy for two reasons: the sea routes tended to be the safest and easiest way to travel across the Roman Empire and the metropolitan areas that connected these routes had a strong population of diaspora Jews.
Second, the early missionaries would evangelize within these communities of diaspora Jews first. We see this within the Acts as Paul’s first stop when he reached a new city was almost always the local synagoguge. It wasn’t until he had worn out his welcome in the synagogue that he would move on to evangelizing within the city proper. These diaspora communities provided a place of doctrinal and cultural continuity from which the Christian message could be preached.
Third, the early missionaries placed an emphasis on both the sense and the intellect. The coastal metropolitan areas were not only home to diaspora Jews but also to a pagan tradition that placed a heavy emphasis on combining the sensual with the intellectual. This was the combined religious/philosophical bent of the Greeks which provided a rich bed from which a Christian metaphysics and philosophy would arise. Acts 17:22-31 demonstrates how Paul uses this combined appeal of the sensual and the intellectual at the Areopagus. Paul begins from a position in which he appears to agree with the Stoics against the Epicureans. From there, he begins to use their own philosophy to show that while they have good ideas, and they have an appropriate sense of God in creation, they are ultimately wrong and their philosophy needs a correction that can only be found in Christianity. This appeal to a shared doctrinal, cultural, and philosophical heritage between Jews, pagans, and Christians became the basis for Christianity’s early spread.
A late example of the power this approach had comes from Julian the Apostate (A.D. 332-363) who attempted to reignite paganism within the Roman Empire and drive Christianity out of the governing classes. Writing in the Letter to Arsacius he states:
“The religion of the Greeks does not prosper as I would wish, on account of those who profess it….Why then do we think that this [his arrival as a pagan reformer] is sufficient and do not observe how the kindness of Christians to strangers, their care for the burial of their dead, and the sobriety of their lifestyle has done the most to advance their cause?…For it is disgraceful when no Jew is a beggar and the impious Galileans support our poor in addition to their own…”
Christianity won out over the pagans because it was willing to live with them, suffer with them, and offer a corrective to wrong belief. Not by overthrowing those beliefs, but by acknowledging that in searching for the truth the pagans had come close, but not close enough. Those erroneous beliefs could be corrected and redirected through education and a shared culture. For the Jew, the Christian could point to a shared religious history. To the pagan, the Christian could point to a shared belief in the appropriateness of the life of the mind and an appreciation for God’s created world. Philip Schaff puts it well:
“The church succeeded to the inheritance of all nations, but could only by degrees purge this inheritance of its sinful adulterations, pervade it with her spirit, and subject it to her aims; for she fulfills her mission through human freedom, not in spite of it, and does not magically transform nations, but legitimately educates them.”1
 Philip Schaff, History of the Christian Church: From the 1st to 19th Century, Vol. 3, Chap. 8, Sect. 106.