These verses are quite something; Jude has an interesting way with words…
In the very same way, on the strength of their dreams these ungodly people pollute their own bodies, reject authority and heap abuse on celestial beings.
Our journey begins with connective language indicating that Jude’s opponents are doing the same thing that was being done in the previous verses, separating people from their relationships with God. Please keep in mind as we continue, that the issue here for Jude isn’t so much that these people are doing improper things, but that they are encouraging others to turn their backs on their covenant relationship with Christ.
These dreamers (or on the strength of their dreams) is another interesting turn of phrase. The Israelites were warned against prophets and dreamers who would lead them into rebellion against God. (Deut. 13:15; Jer. 27:9) It seems that these false prophets, based upon dreams were leading the people away from their covenant relationship, just as Jude is claiming about the first century false teachers. Further, these people are “ungodly” and “pollute their own bodies” and do not respect authority. This pollution is a reference to their immoral sexual practices.
They also reject authority. The word rendered “authority” here is kyriotēs meaning “dominion, power, lordship” and is rendered “powers” in Col. 1:16 and “dominion” in Eph. 1:21. This is a reference to angelic beings, like those spoken of in Heb. 2:2 “message spoken by angels”. In short, the “authority” they are rejecting is that of the angels of God who brought the Law to the people; the very morality they are flaunting in their behavior. These people are heaping abuse on the messengers of God Himself!
But even the archangel Michael, when he was disputing with the devil about the body of Moses, did not himself dare to condemn him for slander but said, “The Lord rebuke you!”
These people are so out of line in heaping their abuse on angels, they are doing something that the Archangel Michael wouldn’t even do to Satan. Jude is recalling a story that is not found anywhere in Scripture. According to the early writings of Clement of Alexandria, Origen and Didymus, Jude found this account in The Assumption of Moses, a Jewish work dating from the first century that currently exists in fragment form.
Yet these people slander whatever they do not understand, and the very things they do understand by instinct—as irrational animals do—will destroy them.
These characters slander what they don’t understand. I would think that a Christian of our age would understand exactly what is meant here, for we deal with that almost every day in the popular media. What these characters understand by instinct, like any animal would, will destroy them. Yes, they apparently understand sex, and their immorality will be their undoing.