Despite the potential importance of Cerinthus for understanding the development of Christianity in Asia Minor, his teaching and legacy have been obscured in the patristic reports about him. One can identify two contrasting images of Cerinthus in the sources: an early "gnostic" in conflict with the Johannine tradition (Irenaeus); a Judaistic chiliast who opposed the apostles (beginning with Gaius of Rome and culminating with Epiphanius of Salamis). This has resulted in an impasse in understanding the early heretic and his significance which has continued up to the present. This article proposes a way of sorting out the traditions concerning Cerinthus and making sense of the earliest accounts. Upon critical investigation, Irenaeus' profile of Cerinthus as an early ditheistic and adoptionistic Christian emerges as essentially unproblematic and plausible. But most elements of the "Judaic" portrait are shown to be the product of confusion. What remains from this portrait, namely Cerinthus' chiliasm, may however be understood as consistent with Irenaeus' report if it was the type of chiliasm taught later by Marcion. The article shows how Cerinthus' chiliasm finally can be accounted for as a natural, not a heterogenous, part of his dualizing and anti-Judaistic system. It suggests that a coherent picture of Cerinthus' teaching can now be of help in elucidating the background and history of the Johannine churches and the rise of Christian gnosticism.