How did Paul's new converts fresh out of paganism survive with so little teaching?

Les explains that Paul did not remain long in most places. Every place Paul established a church was usually only for a week or two; Antioch was a year and a half, but Thessalonica may have been only a couple of weeks. In contrast, the Church of Jerusalem prospered because the apostles stayed there year in and year out among the Jews in Israel. Les says he cannot understand how these new believers fresh out of paganism made it, except by the miraculous power of God, because Christianity was now to take off and begin permeating the whole Roman Empire. He also notes that even the carnal Corinthians were believers. Their pagan lifestyle included the temple of the goddess Aphrodite above the city with 1,000 female priestesses, who went down into Corinth at night, confronting the men every night of the week. That is why the Bible is so explicit.