Jude 6 is a parallel reference to 2Pet. 2.4. Both of these passages refer to angelic judgment without any idea of human/angel sexual union. I reject any Jewish myths about angel/human cohabitation, and both Peter and Jude reject this notion as well. Also, only scripture is without error and not Jewish legendary texts, which some want to reference as authoritative, but are not.
While not conclusive, Lk. 20.35 seems to point to no cohabitation of any kind in the angelic realm, But those who are considered worthy of taking part in the age to come and in the resurrection from the dead will neither marry nor be given in marriage (NIV). Therefore, I would argue that no reproduction or sexual desire is possible in the heavenly state. Further, it was through and for Jesus that all the heavenly hosts were created, For in him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things have been created through him and for him (Col. 1.16 NIV). If He created all angelic persons, then, they could not cohabit to create other spiritual beings by themselves. The origin of spirits rests with God.
Exposition of Jude 4-7
For certain individuals whose condemnation was written about long ago have secretly slipped in among you. They are ungodly people, who pervert the grace of our God into a license for immorality and deny Jesus Christ our only Sovereign and Lord. Though you already know all this, I want to remind you that the Lord at one time delivered his people out of Egypt, but later destroyed those who did not believe. And the angels who did not keep their positions of authority but abandoned their proper dwelling—these he has kept in darkness, bound with everlasting chains for judgment on the great Day. In a similar way, Sodom and Gomorrah and the surrounding towns gave themselves up to sexual immorality and perversion. They serve as an example of those who suffer the punishment of eternal fire. (NIV)
Those who want to see sexualized angels in this text will have to link all of Jude’s examples together to show a consistent description of sexual sin. But that cannot be done since Jude’s first example is of disbelief. The Israelites who came out of Egypt were discouraged by the spies’ bad report and wanted to choose a leader to go back to Egypt, and consequently were judged to die in the wilderness (see Num. 14. 1-4, 20-23).
The next problem for those who see a sexual connotation in Jude 6 is the smuggling of homoion (the Greek word meaning “similar”) to the first part of verse 7. Hos occurs instead which is an adverb meaning “like manner.” They may retort that hos means the same thing but they miss the flow of the text. First, homoion (an adjective meaning “similar”) is inextricably and clausal in connection to the cities who were like Sodom and Gomorrah. The adjective cannot be moved.
The second reason that Sodom’s sin cannot be connected to the angels is that what “like manner” (hos) refers to is not the sexual sin of Sodom but of the same judgment. Jude begins by speaking about the infiltrator’s judgment (condemnation-vs.4). Jude then gives examples of other groups who will be judged for various things. The overriding common theme is the condemnation these groups are facing. Sodom will be judged in like manner as angels but for different reasons.
The infiltrators in Jude’s day exhibited the same type of sin as Sodom in that they were immoral (vs.4) and polluted their bodies, and therefore Jude, again, uses homoion, in vs. 8, to indicate their sameness. Therefore, only the present infiltrators were similar to Sodom. Neither the people who disbelieved, nor the angels who were separated into darkness have any record of sexual sin.