Here are some interesting thoughts from the Bible Exposition Commentary:

Jude was not content simply to remind his readers to pay attention to what Peter had written. He wanted to add his own words of warning by describing what the false teachers were like and what they would do to the church. The Spirit of God led Jude to describe the characteristics of the apostates, reinforcing Peter’s words and, at the same time, adding information. Jude 8–16 and 2 Peter 2:1 parallel and supplement each other.
But why this seemingly needless repetition? The Apostle Paul gave the answer: “To write the same things to you, to me indeed is not grievous, but for you it is safe” (Phil. 3:1). Parents repeat warnings and instructions to their children, and sometimes the children reply, “I know that! You’ve already told me a million times!” But wise parents know that some things must be said again and again for the safety and welfare of their children—whether the children want to hear them or not!
All that Jude wrote about the apostates in these verses may be summarized in three statements.

They Reject Divine Authority (Jude 8–11)
All authority comes from the throne of God, whether it is authority in the home, the church, or the state. Those who exercise authority must first be under authority, accountable to God. But the false teachers reject divine authority and set themselves up as their own authority.
The cause of their rebellion is found in the word dreamers (Jude 8). These people live in a dreamworld of unreality and delusion. They believe Satan’s lie (Gen. 3:5). Having turned away from God’s truth, they feed their minds on false doctrine that inflates their egos and encourages their rebellion. Jude 10 informs us that the apostates are ignorant people who do not know what they are talking about! Jude echoed Peter’s description of these men as “brute beasts” (2 Peter 2:12, 22). Animals live by natural instinct, and so do the apostates. When men rebel against God, they sink to the level of beasts.
The course of their rebellion was clearly described by Jude. As a result of their rebellion and pride, they “defile the flesh,” living to satisfy their animal desires. When a person despises God’s authority, he feels free to disobey God’s laws and live as he pleases. What he forgets is that those laws have penalties attached to them so that he cannot disobey and escape the consequences.
They also use their tongues to express their rebellion against God (Psalm. 12:4) The phrase speak evil in Jude 8 and 10 simply means “to blaspheme.” Blasphemy involves much more than taking God’s name in vain, though that is at the heart of it. A person blasphemes God when he takes His Word lightly and even jokes about it, or when he deliberately defies God to judge him (Ps. 73:9, 11)
The consequence of their rebellion is seen in their own ruin (Jude 10). They defile themselves (Jude 8) and they destroy themselves, yet they have the idea they are promoting themselves! (Ecclesiastes 8:11). The way of rebellion is the way to ruin.
Arrogant speech is a dangerous thing, and so is despising the authority that God has established. Even the Archangel Michael (Dan. 10:13) did not dare to rebuke Satan, but respected the authority given to him by God. The name Michael means “Who is like God?” Ironically, Satan had said in his rebellion, “I will be like the Most High!” (Isa. 14:14) and his offer to men is, “... you shall be as gods” (Gen. 3:5).
We have no information about the conflict between Satan and Michael over the body of Moses. When Moses died, the Lord buried him and no one knew where the tomb was located (Deut. 34:5–6). No doubt the Jewish people would have made a shrine out of the tomb and fallen into idolatry, so God kept the information to Himself. The text tells us that no one knew the place, so perhaps Satan did know the place and tried to claim Moses’ body for himself. Inasmuch as Satan does have a certain amount of authority in the realm of death he may have felt he had a right to interfere (Heb. 2:14–15).
The point is that Michael did not rebuke Satan, but left that to the Lord. It is a dangerous thing for God’s people to confront Satan directly and to argue with him, because he is much stronger than we are. If an archangel is careful about the way he deals with the devil, how much more cautious ought we to be! While it is true that we share in the victory of Christ, it is also true that we must not be presumptuous. Satan is a dangerous enemy, and when we resist him, we must be sober and vigilant (1 Peter 5:8–9).
“The Lord rebuke you!” has a parallel in Zechariah 3:1–5. The prophet had a vision of the high priest standing before God’s throne in defiled garments, symbolizing the sinful condition of the nation Israel after the Babylonian Captivity. Satan had every right to accuse the people (see Rev. 12:9–11), except for one thing: they were the chosen ones of God, His covenant people, and He would not go back on his Word. God forgave His people, gave them clean garments, and warned them to walk in his ways. This is an Old Testament illustration of 1 John 1:5–2:2.
The condemnation of the false teachers is given in Jude 11: “Woe to them!” Jude cited three examples from the Old Testament to illustrate the enormity of their sins, three men who rebelled against God’s authority and who suffered for it.
Cain rebelled against God’s way of salvation (Gen. 4; 1 John 3:11–12). By clothing Adam and Eve with the skins of slain animals (Gen. 3:21), God made it clear that the only way of forgiveness is through the shedding of blood. This is the way of faith, not the way of good works (Ephesians. 2:8–10). But Cain rejected this divinely authorized way and came to the altar with the fruits of his own labour. God rejected Cain’s offering because God rejected Cain: his heart was not right before God. It was by faith that Abel’s sacrifice was offered, and that was why God accepted it (Heb. 11:4).
The “way of Cain” is the way of religion without faith, righteousness based on character and good works. The “way of Cain” is the way of pride, a man establishing his own righteousness and rejecting the righteousness of God that comes through faith in Christ (Rom. 10:1–4; Phil. 3:3–12). Cain became a fugitive and tried to overcome his wretchedness by building a city and developing a civilization (Gen. 4:9ff). He ended up with everything a man could desire everything except God, that is.
We have already studied “the way of Balaam” (see 2 Peter 2:15–16). The “way of Balaam” is selling one’s gifts and ministry just for the purpose of making money. It is using the spiritual to gain the material (see 1 Thessalonians. 2:5–6; 1 Tim. 6:3–21). The false teachers were greedy for material gain and, like Balaam, would do anything for money. The “error of Balaam” is thinking that they can get away with this kind of rebellion. Balaam was a true prophet of God, but he prostituted his gifts and sought to destroy God’s people. God turned Balaam’s curses into blessings (Deut. 23:4–5).
While we are on the subject of Balaam, we might note the “doctrine of Balaam” (Rev. 2:14) which is, “You can violate your separated position and get away with it!” He told King Balak that the fastest way to destroy Israel would be to corrupt the nation by having the people defile themselves with the heathen nations around them. “You are God’s chosen people,” was the argument. “Certainly a little friendship with your neighbors will not hurt you!” [Sounds a bit like Rick Warren's attitude to other religions] It was “turning the grace of... God into lasciviousness” (Jude 4), and God judged both Israel and Balaam.
The story of Core (Korah) is found in Numbers 16, and it too centers on rebellion against authority. Korah and his followers resented the leadership of Moses and dared God to do anything about their rebellion. In speaking against Moses, they were speaking against the Lord who had given Moses his authority. This is a warning to us today, for it is so easy to speak against spiritual or governmental leaders in a careless way (see Titus 3:1–2). God judged Korah and his followers and established clearly the authority of His servant, Moses.
Cain rebelled against God’s authority in salvation, for he refused to bring a blood sacrifice as God had commanded. Balaam rebelled against God’s authority in separation, for he prostituted his gifts for money and led Israel to mix with the other nations. Korah rebelled against God’s authority in service, denying that Moses was God’s appointed servant and attempting to usurp his authority.
It is interesting to note the verbs that Jude used in this verse. The apostates “traveled on the road” of Cain, “gave themselves over to” the error of Balaam, and “perished” in the rebellion of Korah. The tragedy of rejecting authority!

They Resort to Deliberate Hypocrisy (Jude 12–13, 16)
Jude 12 and 13 present six vivid pictures of the false teachers and help to explain why they are dangerous to the church.
Filthy spots (Jude 12). Peter called them spots and blemishes (2 Peter 2:13). These men had invaded the “love feasts” in the local assemblies, but all they did was defile them. Instead of adding to the sanctity of the occasion, they detracted from it, like Judas at the last Passover that Jesus celebrated with His disciples. The tragedy is that the members of the assembly did not realize the true character of these men! They thought the men were spiritual!
The Greek word translated “spots” can also mean “hidden rocks.” The mariner who is unaware of the hidden rocks can quickly wreck his ship. The pilot must always be alert, for waters that look calm and safe can contain treacherous reefs. Spiritual leaders must constantly be on guard.
Selfish shepherds (Jude 12). The word translated “feeding” means “shepherding.” Instead of shepherding the flock and caring for the needs of the people, these apostates only take care of themselves. Jude may have had in mind Isaiah 56:10–12 and Ezekiel 34:1, where the prophets condemned the political and spiritual leaders of the nation (“shepherds”) for exploiting the people and caring only for themselves.
It is a serious thing to be a shepherd over God’s flock. Our example must be Jesus Christ, the Good Shepherd who gave His life for the sheep. False shepherds use and abuse people in order to get what they want, and yet all the while, the people love it! Paul marveled at this when he wrote 2 Corinthians 11:20—“You don’t mind, do you, if a man takes away your liberty, spends your money, takes advantage of you, puts on airs, or even smacks your face?”
These selfish shepherds do all of this “without fear.” They are an arrogant lot! This is the difference between a true shepherd and a hireling: the true shepherd cares for the sheep, while the hireling cares only for himself. “Woe be to the shepherds of Israel that do feed themselves! Should not the shepherds feed the flocks?” (Ezek. 34:2) But these apostates ought to be afraid, for their judgment is coming.
Empty clouds (v. 12c). Clouds that promise rain, but fail to produce, are a disappointment to the farmer whose crops desperately need water. The apostates look like men who can give spiritual help, and they boast of their abilities, but they are unable to produce (2 Peter 2:19).
The Word of God is sometimes compared to the rain and the dew. “My doctrine shall drop as the rain, my speech shall distill as the dew” (Deut. 32:2). Isaiah 55:10 compares God’s Word to the rain and snow from heaven that bring fruit on the earth. Like the clouds in the sky, the false teachers may be prominent and even attractive; but if they cannot bring rain, they are useless.
Dead trees (v. 12d). The picture is that of an orchard in autumn, the time when the farmer expects fruit. But these trees are fruitless! “Ye shall know them by their fruits” (Matt. 7:16). Those who teach and preach the Word have the responsibility of feeding others, but the false teachers have nothing to give. Not only are they fruitless, but they are also rootless (“plucked up by the root”); this is why they are “twice dead.” What a contrast to the godly man in Psalm 1:3!
One of the evidences of true salvation is producing spiritual fruit. The seed that fell on the hard soil, the shallow soil, and the crowded soil did not produce fruit; but the seed that fell on the “good ground” did produce fruit (Matt. 13:1–9, 18–23). No matter how much of the Bible the false teachers may quote, the seed is not producing fruit in their own lives or through their ministries. Why? Because they have no spiritual roots. They lack spiritual life.
Fruit has in it the seed for more fruit (Gen. 1:11–12). One of the evidences that a ministry is truly of God is that the fruit multiplies. Manufactured “results” are sterile and dead, but true fruit continues to grow and reproduce itself in the lives of others.
Raging waves (v. 13a). I personally do not enjoy being in or on the ocean (I am not a good swimmer). However, I do enjoy sitting by the ocean and contemplating its grandeur and power. But I certainly would not want to be either in or on the ocean in a storm! There is great power in those waves, as many a mariner has discovered. But Jude compared the apostates to “raging waves of the sea” not because of their power, but because of their pride and arrogant speech (Jude 16). Like the swelling of the sea, they make a lot of noise, but what do they produce? Have you ever walked along the beach the morning after a storm and seen the ugly refuse that has been deposited on the shore?
Jude may have had Isaiah 57:20 in mind. All that the “great swelling words” of the apostates can produce is foam and flotsam! The true teachers of the Word bring up the treasures of the deep, but the false teachers produce only refuse. And what they boast about, they really ought to be ashamed of! (see Phil. 3:19)
Wandering stars (Jude 13). Jude was not referring to fixed stars, planets, or comets, because they have definite positions and orbits. He was referring to meteors, falling stars that suddenly appear and then vanish into the darkness, never to be seen again. Our Lord is compared to a star (Rev. 2:28; 22:16), and Christians are to shine as stars in this dark world (Phil. 2:15). Fixed stars can be depended on to guide the traveler through the darkness, but wandering stars can only lead him astray.
One of my hobbies is collecting books of sermons, not only by famous preachers, but also by obscure and forgotten men whose names once were famous. I have noticed that many a “pulpit beacon” has turned out to be a fallen star! It is disturbing to read histories and biographies and see how “the mighty have fallen.” For the most part, those who have been true to the Word are ministering yet today as lights shining in the darkness, while the preachers of false doctrine have fallen into oblivion.
God has reserved chains of darkness for the rebellious angels (Jude 6), and He has reserved “the blackness of darkness forever” for apostate teachers. Beware of following a falling star! It will lead you into eternal blackness!
As you review these six pictures of the false teachers, you can easily see how dangerous they are and how important it is for the church to keep them out.
Murmurers and complainers (v. 16). Jude 16 completes the description and emphasizes even more why they are so dangerous: they are out to please themselves by taking advantage of others. This reminds us of Peter’s statement (2 Peter 2:14) or, as Phillips translates it, “Their technique of getting what they want is, through long practice, highly developed.” They give the impression that they are out to help you, but they are interested only in gratifying their own lusts...
The false teachers also use “great swelling words” to impress ignorant people. Peter called their speeches “great swelling words of vanity” (2 Peter 2:18). They impress people with their vocabularies and oratory, but what they say is just so much “hot air.” They also use flattery to manipulate their listeners. They “bow and scrape” and pay compliments to others, if it is to their advantage.
Knowing these things, we are amazed that anybody would listen to these apostates and follow them; but many people are doing it today! There is something in fallen human nature that loves a lie and is willing to follow it, no matter where it may lead. But the success of the apostates is only temporary, for their judgment is coming.

They Receive Their Due Penalty (Jude 14–15)
All that we know about Enoch from Scripture is found in Genesis 5:18–24; Hebrews 11:5; and these two verses in Jude. He is called “the seventh from Adam” to identify him as the godly Enoch, since Cain had a son of the same name (Gen. 4:17). In a society that was rapidly being polluted and destroyed by sin, Enoch walked with God and kept his life clean. He also ministered as a prophet and announced the coming judgment.
Bible scholars tell us that this quotation is from an apocryphal book called The Book of Enoch. The fact that Jude quoted from this non-biblical book does not mean the book is inspired and trustworthy, any more than Paul’s quotations from the Greek poets put God’s “seal of approval” on everything they wrote. The Spirit of God led Jude to use this quotation and make it a part of the inspired Scriptures.
When Enoch originally gave this message, it is possible that he was also referring to the coming judgment of the Flood. He certainly lived in an ungodly age, and it seemed that sinners were getting away with their evil deeds. But Enoch made it clear that judgment was coming and that the ungodly would get what was coming to them!
However, the final application of this prophecy is to the world in the end times, the very judgment that Peter wrote about in 2 Peter 3. The false teachers mocked this prophecy and argued that Jesus Christ would never come and God would never send judgment. But their very attitude was proof that the Word is true, for both our Lord and His Apostles, as well as the prophets, said that scoffers and mockers would appear in the last days (2 Peter 3:1–4). Enoch gave his prophecy thousands of years ago! See how patient God has been with those who have rebelled against Him!
What does Enoch’s prophecy say about the coming judgment? It will be a personal judgment: God Himself will come to judge the world. He will not send a famine or a flood, nor will He assign the task to an angel. He Himself will come. This shows the seriousness of the event, and also its finality. “Behold, the Judge standeth before the door” (James 5:9).
Though it is a personal judgment, our Lord will not judge alone; the saints of God will be with Him. The word saints in Jude 14 means “holy ones” and can also refer to the angels (Deut. 33:2; Matt. 25:31). However, we know from Revelation 19:14; Colossians 3:4; and 1 Thessalonians 3:13 that the people of God will accompany the Lord when He returns to earth to defeat His enemies and establish His righteous kingdom (cf. 1 Cor. 6:2–3). Over the centuries, the people of God have suffered at the hands of the ungodly, but one day the tables will be turned.
It will be a universal judgment. He will execute judgment “upon all”—none will escape. Just as the Flood destroyed all who were outside the ark, and the fire and brimstone destroyed all in Sodom and Gomorrah except Lot and his wife and two daughters, so the last judgment will encompass all the ungodly. The word ungodly is used four times in this one verse! It will be “the day of judgment and perdition [ruin, destruction] of ungodly men” (2 Peter 3:7).
It will be a just judgment. God will convict (“convince”) them of their sins, declare them guilty, pass sentence on them, and then execute the punishment. There will be a Judge, Jesus Christ (John 5:22), but no jury. There will be prosecution, but no defense; for every mouth will be stopped (Rom. 3:19). There will be a sentence, but no appeal, for there can be no higher court than God’s final judgment. The entire procedure will be just, for the righteous Son of God will be in charge.
The Lord will have the record of their “ungodly deeds.” He will also have a record of their motives and hidden desires as they committed these deeds and even these will be ungodly! He will recall the “hard speeches” (Jude 15) that they uttered against the Lord. The word hard carries the idea of “rough, harsh, stern, uncivil.” After all, these people were “murmurers” and “complainers” (Jude 16) and spoke harsh things against God. They were not “afraid to speak evil of dignities” (2 Peter 2:10), but at the judgment their words will testify against them. They spoke “great swelling words” (2 Peter 2:18; Jude 16), but at the judgment their great words will bring great wrath.
There are times when God’s children ask, “Lord, how long shall the wicked, how long shall the wicked triumph? How long shall they utter and speak hard things? and all the workers of iniquity boast themselves?” (Ps. 94:3–4) The answer is given in Psalm 50:3—“Our God shall come, and shall not keep silence: a fire shall devour before Him, and it shall be very tempestuous round about Him.”

Remember God’s Word (Jude 17–19)

From the very beginning, Satan has attacked the Word of God. “Has God said?” was his opening thrust when he led Eve into disobedience in the Garden (Gen. 3:1). Once we begin to question God’s Word, we are vulnerable to Satan’s other attacks, for only the truth of the Word can protect us from the lies of the devil. “To the Law and to the testimony: if they speak not according to this Word, it is because there is no light in them” (Isa. 8:20).
Remember who gave the Word (Jude 17). While our Lord had many disciples, He selected only a few to be apostles. The word means “one who is sent with a commission.” In order to qualify, a believer had to be a witness of the resurrection of Christ (Acts 1:21–22; 1 Cor. 9:1). The Apostles lived with Christ during His ministry, learned from Him, and were sent by Him into all the world to carry the Good News of salvation.
Wherever there is the authentic, the counterfeit will appear; this happened in the early church. False apostles and teachers began to appear, and it was necessary to develop a system to protect the church against false prophecies and forged letters. Since Christ had committed “the faith” (Jude 3) to His Apostles, one of the main tests in the early church was, “Is this what the Apostles taught?” When the church assembled the New Testament books, it was required that each book be written either by an apostle or by someone closely associated with an apostle. Apostolic teaching was, and still is, the test of truth.
Jude mentioned the words that were “spoken” by the Apostles, because originally there were no New Testament epistles. Over the years, inspired letters were written by Paul, Peter, and John; we have these letters in our New Testament. We also have a record of some of their sermons in the Book of Acts. We no longer depend on tradition since we have the completed Scriptures, both the Old Testament and the New.
Whenever somebody offers you a “new revelation,” test it by what the Apostles wrote and by what Jesus Christ taught. You will soon discover that the “revelation” is a lie.
Remember what they said (Jude 18). They prophesied that, in these last days, mockers would come who would deny the Word of God. Jude echoed what Peter had written (2 Peter 3:3ff), but Paul and John also warned their readers about the apostates (1 Tim. 4; 2 Tim. 3; 1 John 2:18ff; 4:1–6). When a warning is given so many times, it is necessary for us to take it seriously!
The phrase “walking after their own desires” appears in 2 Peter 3:3 and Jude 16, 18, and it explains why the apostates deny God’s truth: they do not want God to tell them how to live. They want to satisfy their own sinful desires, and the Word of God condemns their selfish way of life. When a person says, “I have intellectual problems with the Bible,” he probably has moral problems because the Bible contradicts what he is doing. The only sure way to know the truth of the Bible is by obeying it (John 7:17).
Before Satan can substitute his own lies, he must get rid of the truth of God’s Word. If he cannot argue it away, he will laugh it away, and he can usually find somebody to laugh with him.
Remember why they said it (v. 19). The false teachers want to divide the church and lead people out of the true fellowship into their false fellowship. “Also of your own selves shall men arise, speaking perverse things, to draw away disciples after them” (Acts 20:30). Their appeal is usually, “We have a deeper knowledge of the Word that your church doesn’t have! We have a better understanding of prophecy, or of the Christian life, than you do.” They offer a “higher quality” religion than that of the Apostles.
Not only do false teachers divide the church, but they also deceive the church, because they are “sensual, having not the Spirit.” The word sensual means the opposite of “spiritual.” This is the way Paul used it in 1 Corinthians 2:14–16, where it is translated “natural.” (The Greek word is psukikos, which means “soulish.”) Because the false teachers do not have the Spirit of God, they must function on their natural “soul power” alone.
One of the tragedies in ministry today is that some of God’s people cannot discern between “soul ministry” and the true ministry of the Spirit. There is so much “religious showmanship” these days that the saints are confused and deceived. Just as there was “false fire” in the tabernacle (Lev. 10:1), so there is “false fire” today in the church; therefore we must exercise careful discernment.
How can we discern between the “soulish” and the “spiritual”? By using the Word of God which is able to divide soul and spirit (Heb. 4:12); and by paying close attention to the witness of the Spirit of God within (Rom. 8:16). A “soulish” ministry magnifies man, but the Spirit glorifies Jesus Christ. When the Spirit is ministering through the Word, there is edification; but when the soul is merely “manufacturing” a ministry, there is entertainment or, at best, only intellectual education. It takes the Spirit of God to minister to our spirits and to make us more like Jesus Christ.
Wiersbe, W. W. (1996, c1989). The Bible exposition commentary. "An exposition of the New Testament comprising the entire 'BE' series"--Jkt. (Jud 14). Wheaton, Ill.: Victor Books.