Religion
In reply to the discussion: Brian Zahnd: No, God didnt command genocide in the Old Testament [View all]Act_of_Reparation
(9,116 posts)Early Christians lacked political influence and couldn't engage in the kind persecution you describe until they were granted legal, and ultimately official, status within the Empire. They did, however, engage in sectarian conflict with the Jews and with each other.
The first three centuries of Christianity saw the development of Christian orthodoxy, which necessarily entailed the suppression of heretics like the Marcionites and the Gnostics. Whether or not this involved physical violence on some level is anyone's guess (as you note, the Church was largely underground at this point) but the early factions did exert their internal political influence against each other. At the very least, there were excommunications, which were a much larger deal in late antiquity than they are today.