But to a remarkable and in some ways unexpected degree, the Jews managed to operate within Roman culture. For the Romans, Christianity was far worse. First, it had no ancestral home. In their ordered religious geography, Romans expected deities to be from somewhere: Isis from Egypt, Mithras from Persia, the Jewish god from Judaea. The Christian god was rootless, claimed to be universal and sought more adherents. All kinds of mystical moments of enlightenment might attract new worshippers to (say) the religion of Isis. But Christianity was defined entirely by a process of spiritual conversion that was utterly new. What is more, some Christians were preaching values that threatened to overturn some of the most fundamental Greco-Roman assumptions about the nature of the world and of the people within it: that poverty, for example, was good; or that the body was to be tamed or rejected rather than cared for. All these factors help to explain the worries, confusion and hostility of Pliny and others like him. At the same time, the success of Christianity was rooted in the Roman Empire, in its territorial extent, in the mobility that it promoted, in its towns and its cultural mix. From Pliny’s Bithynia to Perpetua’s Carthage, Christianity spread from its small-scale origins in Judaea largely because of the channels of communication across the Mediterranean world that the Roman Empire had opened up and because of the movement through those channels of people, goods, books and ideas. The irony is that the only religion that the Romans ever attempted to eradicate was the one whose success their empire made possible and which grew up entirely within the Roman world.
More: read SPQR: A History of Ancient Rome