Fate: Condemned by Irenaeus, Clement of Alexandria, and Hippolytus. Tatian’s Diatessaron — a harmony of the four Gospels — was used as the standard gospel text in the Syrian church for two centuries before being suppressed in favor of the four separate gospels (~423 AD under Theodoret of Cyrrhus, who reportedly destroyed 200 copies).

Tatian (~120–180 AD) was a student of Justin Martyr who, after Justin’s martyrdom, returned to Syria and founded the Encratites (from Greek enkrateia, self-control). The Encratites rejected marriage as fornication, prohibited meat and wine (using water in the Eucharist — hence also called Aquarians or Hydroparastatae), and viewed sexual reproduction as participation in the demiurge’s material creation. Marriage was the mark of the devil. This extreme asceticism likely drew on Syrian Christian traditions that read Jesus’s call to celibacy as literal and absolute. The Encratite position forces a sharp question: if the material world and biological reproduction are evil, is the incarnation itself compromised? Orthodox theology says no — hence the condemnation.

What happens when a group is declared heretical: The process is rarely sudden. It typically begins with episcopal letters condemning a teaching, escalates to synodal condemnation at a regional council, and — after Constantine — can be ratified by an ecumenical council backed by imperial authority. Once condemned: (1) Leaders are excommunicated, exiled, or — in later centuries — handed to secular authorities for execution. (2) Writings are ordered burned; possession becomes a criminal offense. Eusebius records that after Nicaea, Constantine ordered Arian books destroyed under penalty of death. The same logic applied to Gnostic texts — which is why the Nag Hammadi library was buried in a sealed jar around 367 AD, the same year Athanasius’s Easter letter listed the NT canon and ordered non-canonical books removed from churches. (3) Communities are dissolved by force where state power reaches; in regions beyond imperial reach they survive for centuries. (4) Memory is controlled — the only surviving accounts of most heresies are hostile summaries by their opponents (Irenaeus, Tertullian, Epiphanius’s Panarion), meaning we are largely reading prosecution briefs, not the groups’ own self-understanding.