Ante-Nicene Fathers/Volume V/Cyprian/The Treatises of Cyprian/Three Books of Testimonies Against the Jews/Book III/Part 78

78. That we must not speak with heretics.

To Titus: &#8220;A man that is an heretic, after one rebuke avoid; knowing that one of such sort is perverted, and sinneth, and is by his own self condemned.&#8221; Of this same thing in the Epistle of John: &#8220;They went out from among us, but they were not of us; for if they had been of us, they would doubtless have remained with us.&#8221; Also in the second to Timothy: &#8220;Their word doth creep as a canker.&#8221;