Acts 20:30

The heretics, Hymenæus and Alexander (1 Timothy 1:20), also Diotrephes (3 John 1:9), were presbyters of Ephesus. From the Epistles of St. John, which were written at Ephesus, we learn that the Ephesian heresies were of the Gnostic and Docetic types. St. John's chief opponent at Ephesus was Cerinthus, who taught a Jewish form of Gnosticism.