What does Jude mean that false teachers know things 'naturally as brute beasts'?
Jude means false teachers operate only from the old Adamic nature, not spiritual understanding. They know and live by natural instincts like brute beasts, so they ridicule Scripture they never studied. Their thinking and morals are no higher than the animal world, and in those natural things they corrupt themselves.
Les explains that Jude is identifying false teachers who hawk an adulterated product. They defile the flesh, despise dominion, and speak evil of dignities. They speak evil of things they know not and ridicule the truth of Scripture even though they have never studied it. What they know "naturally" comes from the old Adamic side, as brute beasts. Much of society lives at the level of animals, and these false teachers come from that same level; their thinking is no higher than the animal world. In those natural things they corrupt themselves, living at the moral level of an animal while thinking they are living it up. Jude then pronounces woe on them and calls them spots in the love feast, feeding themselves without fear.
But these speak evil of those things which they know not: but what they know naturally, as brute beasts, in those things they corrupt themselves.
More Questions
What is the source of false teachers' natural knowledge?
What false teachers know naturally comes from the old Adamic side, as brute beasts.
Who is Jude 10 talking about when it mentions false teachers?
Jude 10 is speaking about false teachers who will be deceptive in the closing days.