Jude addresses the last days and all the false religions so we can discern the apostate churches from the biblical ones.
Contending for the Faith
Jude addresses the last days and the false religions that were coming into the church. He does this so we can discern the apostate churches or teachings from the biblical ones. Jude, another name for Judas, was a half-brother of Jesus Christ (Mark 6:3; Matt 13:55), and his purpose for writing this book was to address all the false teachings that were infiltrating the churches in his day. He wanted the church to know how to spot the sheep from the wolves, so he says, “although I was very eager to write to you about our common salvation, I found it necessary to write appealing to you to contend for the faith that was once for all delivered to the saints. For certain people have crept in unnoticed who long ago were designated for this condemnation, ungodly people, who pervert the grace of our God into sensuality and deny our only Master and Lord, Jesus Christ” (Jude 1:3-4). He wants the church to “contend” or fight for the original gospel, once and for all delivered…not this sensual, flesh-oriented religion from Satan we are seeing these days.
The Author of Hebrews tells us plainly that it was “Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world” (Heb 1:1-2). Notice that it’s like how Jude wrote; “God has spoken” (past tense) through the prophets (Old Testament) and the apostles (New Testament, i.e., Eph 2:12-22), and lastly through the Son of God, Jesus Christ (the gospels, epistles, and both Testaments!). We already have our foundation; one that was laid two millennial ago. The Apostle Paul says that believers “are fellow citizens with the saints and members of the household of God, built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone, in whom the whole structure, being joined together, grows into a holy temple in the Lord. In him you also are being built together into a dwelling place for God by the Spirit” (Eph 2:19-22). Again notice that this is all in the past tense. The only part that is present tense is where the church is still being built. The Apostle Peter says, “you yourselves are like living stones being built up as a spiritual house” (1 Pet 2:5).
Since we are being built up on top of this foundation, the day of having apostles and prophets is over. God does not need anyone’s help to give us new revelation. The faith has once and for all been delivered and God is still not making deliveries. He may speak through someone and they may be yielded to the Spirit and may have godly wisdom, but their words are not Scripture. The Canon is closed! In 1 Corinthians 3:11 Paul says that “no one can lay any other foundation than that which is laid, which is Jesus Christ.” We can’t lay a new foundation of apostles and prophets on a two thousand year old structure! That sounds dangerous and the building would have to be condemned, so the church is a 2,000 year-old structure consisting of living stones that rest upon the foundation of the apostles (New Testament) and the Prophets (Old Testament), with Jesus as the Chief Cornerstone (Old Testament and New Testament). And the building goes on…
Another purpose for Jude writing this letter is to encourage the church to persevere by remembering “the predictions of the apostles of our Lord Jesus Christ” (Jude 1:17), that in the last times, scoffers will abound and will be “following their own ungodly passions” (Jude 1:18). Here Jude specifically refers to 2 Peter 3:2-3 which says “that you should remember the predictions of the holy prophets and the commandment of the Lord and Savior through your apostles, knowing this first of all, that scoffers will come in the last days with scoffing, following their own sinful desires.” Obviously, Jude believed Peter’s writings to be sacred or considered the Word of God. As for these false teachers, they walk in the way of Cain in that they openly rebelled against God and His Word, and likely, they do not give Him a proper offering but fill their own pockets. Cain’s anger or jealousy of Abel led him to murder his brother (Gen 4:1-15; 1 John 3:12). When Jude writes that it was for “the sake of gain to Balaam’s error,” he means Balaam enticed Israel into idolatry and sexual immorality for money (Num 22-25). How many of these prosperity preachers have lined their pockets by fleecing the flock; having million dollar homes, yachts, cars, and other expensive riches. Tragically, their end will be like that of Korah who tried to rebel against God’s true leadership and the earth swallowed him and his followers (Num 16:1-12).
These false teachers are very much like “hidden reefs” which cannot be seen but destroy great ships that collide with these unseen “reefs.” They are also like “waterless clouds.” They look good but are really worthless. They are so easily “swept along by winds (doctrinally or culturally relevant) fruitless trees (good for nothing but to be burned)” and “twice dead” meaning that they were never really born again (John 3:3), so they’ll die the second death (Rev 20:11-15). These are they who have reservations for the eternal outer darkness where there will be weeping and gnashing of teeth that Jesus so often spoke about (Luke 13:28).
The Lord is coming to judge these false teachers and their followers. The fact that Jude quotes Enoch’s prophecy, which is an extra-biblical book, does not mean that the Book of Enoch is inspired. Many of these extra-biblical books should be avoided and never considered as Holy Spirit inspired. Besides, the Book of Enoch that we have today is clearly a forgery. The original Book of Enoch was lost thousands of years before Christ. The Jews never quote it. Jude does give an excellent description of the world we see today, saying that “grumblers (against church leaders), malcontents, following their own sinful desires; they are loud-mouthed boasters, showing favoritism to gain advantage” (1:14-16).
Jude 1:22-23 says we are to “have mercy on those who doubt; save others by snatching them out of the fire; to others show mercy with fear, hating even the garment stained by the flesh.” I believe Jude wants us to show mercy for those believers who have doubts, perhaps doubts about their own salvation; maybe even doubts as to whether God actually exists. Have you ever doubted your own salvation or the existence of God at times? This is particularly important for new believers who are new to the faith. As far as the others, we may have to use the fear of God, or literally, “snatch them out of [hell] fire,” telling them about the wrath of God on all sinners. He wants this godly fear to humble them and have them see their need for the Savior. 
If it’s new, it’s not from God; and if it’s from God, it’s not new. That much I know. These so-called “new revelations” trouble me because we are not to add to or take away from God’s Word (Deut 4:2, 12:32; Prov 30:5-6; Rev 22:18-19). We have no need for new revelation. The Bible is sufficient for all and efficient to save. Here Jude concludes by telling us that God “is able to keep you from stumbling and to present you blameless before the presence of his glory with great joy, to the only God, our Savior, through Jesus Christ our Lord, be glory, majesty, dominion, and authority, before all time and now and forever. Amen” (Jude 1:24-25). Either He will present you to God in glory and you will have great joy or you will be “undergoing a punishment of eternal fire” (Jude 1:7), and face the wrath of God forever (Rev 20:12-15). If you haven’t yet trusted in Christ, make today your day of salvation (2 Cor 6:2). Otherwise, you are one breath…one heartbeat…one accident from facing a God and His everlasting wrath.
Here is some related reading for you: Book of Jude Commentary: Study and Summary 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible: English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.