20 But to what they allege and say on behalf of the heretics, that the apostle said, “Whether in pretence or in truth, Christ is preached,” it is idle for us to reply; when it is manifest that the apostle, in his epistle wherein he said this, made mention neither of heretics nor of baptism of heretics, but spoke of brethren only, whether as perfidiously speaking in agreement with himself, or as persevering in sincere faith; nor is it needful to discuss this in a long argument, but it is sufficient to read the epistle itself, and to gather from the apostle himself what the apostle said.
Source: The Epistles of Cyprian (New Advent)