Christianity, as we have seen, began as a tiny offshoot of Judaism. Three centuries later it became the favored and eventually the official religion of the entire Roman Empire. Despite widespread and determined efforts to eliminate the new faith, it survived and grew. By the reign of Constantine (312–337), the first Christian emperor, there were churches in every large town in the empire and in places as distant from each other as Britain, Carthage, and Persia. How did that happen? Where, specifically, did Christianity spread and why did it expand so rapidly?
