He has inhibited discussion by designating admonition as the method of dealing with a heretic- and the first method, too, because he is not a Christian. This is so that he would not seem to require correction again and again and before two or three witnesses as though he were a Christian. He ought to be corrected for the very reason that he is not to be disputed with. In addition, this is said because a controversy over the Scriptures can, clearly, produce no other effect than help to upset either the stomach or the brain.
Tertullian