Gnostic studies mainly depended on the Church Fathers' approach to heresies until the discovery of the Coptic Nag Hammadi codices in 1945. As we are slowly moving away from this patristic approach to Gnosticism, docetism is still defined as a tendency to regard Jesus' body as an appearance, and not as a real incarnate body. Irenaeus' refutation of all heresies presents the Valentinian and Basilidian Christologies as clearly docetist. A comparison of direct Valentinian sources such as the Extracts of Theodotus with Valentinian tractates from Nag Hammadi shows on the contrary that Valentinians had a clear notion of the incarnation. As for the Basilidians, the Elenchos of Ps.-Hippolytus, the Second Logos of the Great Seth and the Coptic Apocalypse of Peter can be used to demonstrate that docetism is not the proper category to interpret Basilidian Christology and Soteriology because the purification of the real body of the Saviour lies at the heart of that system.