Jude 1:11 - Matthew Poole's English Annotations on the Holy Bible

Woe unto them! This is either a lamenting the misery that was to come upon them, or a foretelling it come, not a wishing that it might: see Matthew 11:21 1 Corinthians 9:16. For they have gone in the way of Cain; followed his manners, and fallen under his punishment. Their likeness to Cain, both as to their actions and the event of them, seems to be implied in this and the following clause, as well as it is plainly in the last. Cain hated his brother, and slew him; they hate their brethren, and by their pernicious doctrines and deceits, murder their souls, and probably stir up persecution against their persons. And ran greedily after the error of Balaam for reward; covetousness, to which being excessively addicted, or, as the Greek implies, poured out, they did for the sake of filthy lucre corrupt the doctrine of Christ: see 2 Peter 2:15. And perished in the gainsaying of Core: Korah, (whom he here names alone, as being the ringleader of the rebellion, in which others joined with him, Numbers 16:1), affecting the priesthood, rose up seditiously against Moses and Aaron, and perished in the attempt. These imitate him in their rebellion against Christ himself, the state and order of whose church they seditiously disturb, as well as that of the civil state, in despising dominion, and speaking evil of dignities, and that to their own destruction.