1:19 These are they who separate themselves, sensual, not having the Spirit - Having natural senses and understanding only, not the Spirit of God; otherwise they could not separate. For that it is a sin, and a very heinous one, to separate from the church, is out of all question. But then it should be observed, That by the church is meant a body of living Christians, who are an habitation of God through the Spirit: That by separating is understood, renouncing all religious intercourse with them; no longer joining with them in solemn prayer, or the other public offices of religion: and, That we have no more authority from scripture to call even this schism, than to call it murder.

Jude 1:19 Parallel Commentaries

The Character of Its Teachings Evidences the Divine Authorship of the Bible
Take its teachings about God Himself. What does the Bible teach us about God? It declares that He is Eternal: "Before the mountains were brought forth, or ever Thou hadst formed the earth and the world, even from everlasting to everlasting, Thou are God" (Ps. 90:2). It reveals the fact that He is Infinite: "But will God indeed dwell on the earth? Behold, the heaven and heaven of heavens cannot contain Thee" (I Kings 8:27). Vast as we know the universe to be, it has its bounds; but we must go beyond …
Arthur W. Pink—The Divine Inspiration of the Bible