schism · 172 · Rome
Irenaeus, quoted by Eusebius, is the near-contemporary witness and the source of the shape of the story: he was a hearer of Justin, and expressed no such opinion while he was with him, but after the martyrdom of the latter he left the Church, and becoming exalted with the thought of being a teacher, and puffed up with the idea that he was superior to others, he established a peculiar type of doctrine of his own. What the doctrine amounted to was that marriage is corruption and fornication, and that Adam was not saved. Justin's death is the hinge in every account of it, and Justin has no row on this event because he was seven years dead when it happened. This dataset keeps Tatian and marks him: he is the one person here who leaves the succession he was taught in, and the Diatessaron he made outlasted the condemnation by two centuries in the churches that used it.
To follow the logic of his own asceticism past the point where the church would go with him.
The Encratites, and the awkward fact that the Diatessaron went on being read by people who had condemned its maker.