Bruce Shelley writes,

“Once the Romans discovered what the Christians were up to they were confronted by the problem of toleration in a more exhasperating form than even the Jews had presented. The Jews, after all, were “a sort of closed corporation, a people set apart from others by the mark of circumcision, who lived and worshiped largely by themselves, and did no active proselyting.” The Christians, on the other hand, were always talking about their Jesus. They were out to make Christians of the entire population of the empire, and the rapidity of their spread showed that this was no idle dream. Not only did they, like the Jews, refuse to worship the emperor as a living god, but they were doing their utmost to convince every subject of the emperor to join them in their refusal. From time to time, then, Christians felt the wrath of the empire and it’s people.” (Church History in Plain Language, 38)