Jude New International Version (NIV)
1 Jude, a servant of Jesus Christ and a brother of James,
To those who have been called, who are loved in God the Father and kept for[a] Jesus Christ:
2 Mercy, peace and love be yours in abundance.
The Sin and Doom of Ungodly People
3 Dear friends, although I was very eager to write to you about the salvation we share, I felt compelled to write and urge you to contend for the faith that was once for all entrusted to God’s holy people. 4 For certain individuals whose condemnation was written about[b] 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.
5 Though you already know all this, I want to remind you that the Lord[c] at one time delivered his people out of Egypt, but later destroyed those who did not believe. 6 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. 7 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.
8 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. 9 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!”[d] 10 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.
11 Woe to them! They have taken the way of Cain; they have rushed for profit into Balaam’s error; they have been destroyed in Korah’s rebellion.
12 These people are blemishes at your love feasts, eating with you without the slightest qualm—shepherds who feed only themselves. They are clouds without rain, blown along by the wind; autumn trees, without fruit and uprooted—twice dead. 13 They are wild waves of the sea, foaming up their shame; wandering stars, for whom blackest darkness has been reserved forever.
14 Enoch, the seventh from Adam, prophesied about them: “See, the Lord is coming with thousands upon thousands of his holy ones 15 to judge everyone, and to convict all of them of all the ungodly acts they have committed in their ungodliness, and of all the defiant words ungodly sinners have spoken against him.”[e] 16 These people are grumblers and faultfinders; they follow their own evil desires; they boast about themselves and flatter others for their own advantage.
As Jude is the last book before the book of Revelation, which is almost exclusively about the end times, we see see he has a similar purpose. Because of the ungodliness of those who have slipped into the church, he sees it as a harbinger of the end times. Notice like other false teachers they slip in unannounced, and attend the love feasts, also known as "agape feasts".
They bring in two major errors into the church. They deny Jesus and pervert the grace of God into a license for immortality. We have talked about this is John's letter a lot too. Secondly they assume to have authority over celestial beings, and think their authority allows them to slander them. There is even mention of a dispute between the archangel Michael, and the devil. Michael does not have the power to slander the devil, but the power to say The Lord rebuke you.
Then Jude references several Old Testament situations where people perverted God's grace and used it as a license for immorality. Although God is a merciful God, he does not tolerate evil. He especially hates those who use His name to promote evil. We see cases today, where people use God's name for both immorality and violence, even killing innocent people for the "cause of God". Unless those who do these things repent God's severe judgment is reserved for them as well. If not in this life, certainly in the life to come. These people have also falsely distorted teaching about God.
Believers today also need to be aware of how teachers can distort God's grace as a license to sin. Obedience to God is always apart of following Jesus. Jesus never taught to follow him, but do whatever you want. Instead he said count the cost before you do choose to follow me. One cannot serve two masters, you cannot serve me and money at the same time.