Titus 3:10

An heretic (after a first and second admonition) reject — Avoid, leave to himself. This is the only place, in the whole scripture, where this word heretic occurs; and here it evidently means, a man that obstinately persists in contending about "foolish questions," and thereby occasions strife and animosities, schisms and parties in the church. This, and this alone, is an heretic in the scripture sense; and his punishment likewise is here fixed. Shun, avoid him, leave him to himself. As for the Popish sense, "A man that errs in fundamentals," although it crept, with many other things, early into the church, yet it has no shadow of foundation either in the Old or New Testament.