Those who have by stealth turned the Church away from what it originally held on to in terms of its belief and behaviour will be judged by God. They will not go unpunished. Jude gives 3 examples: the deliverance and destruction of the Exodus and Wilderness years; and here is the second example, the fallen angels.
“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.” (Jude v 6)
Jude raises questions for us and there doesn’t seem to be concrete answers.
Who are these angels? We only have 2 main passages to imagine if this is what Jude is thinking of: Isaiah 14: 12-14 “How you have fallen from heaven, morning star, son of the dawn! You have been cast down to the earth, you who once laid low the nations! You said in your heart, “I will ascend to the heavens; I will raise my throne above the stars of God; I will sit enthroned on the mount of assembly, on the utmost heights of Mount Zaphon. I will ascend above the tops of the clouds; I will make myself like the Most High.” And perhaps Genesis 6: 1-2, “When human beings began to increase in number on the earth and daughters were born to them, the sons of God saw that the daughters of humans were beautiful, and they married any of them they chose.” We may presume this is what Jude is referring to. But from this verse 6 we can see that there is one major point Jude is teaching us:-
No matter the title and status of these ‘ungodly people’ (v4) even if they are seen as leaders within Church it will not prevent them facing judgment. If angels who know the presence of God more than us all and are now bound in chains then what will happen to those who have perverted the grace of Jesus and have denied His Lordship if they live their lives with no repentance?

