Date: Written between A.D. 40 and 80 (most probably between A.D. 60 to 65)
Purpose: To warn that the apostates that had already infiltrated the church and to call the church to arms.
Note: The Book of Jude has been called “the most neglected book in the New Testament” (Douglas J. Rowston).
1 Jude [half-brother of Jesus of Nazareth; cf. Mk. 6:3], a servant of Jesus Christ and a brother of James [the leader of the Jerusalem church; half-brother of Jesus of Nazareth], To those who have been  called, who are  loved by God the Father and  kept [to guard, to watch over, to preserve] by Jesus Christ:
2 Mercy, peace and love [God’s choicest blessings] be yours in abundance.
3 Dear friends, although I was very eager [diligent, earnest] to write to you about [his original intent was to write about the wonders of salvation] the salvation we share, [a more pressing issue caused Jude to change his theme] I felt I had [necessity; the Holy Spirit directed Jude to write something other than what he had originally intended to write about] to write and urge [to encourage, to beseech] you to contend [to struggle for (like an athlete in the games): from the Gr. word epagonizomai from which we get our word “agonize”] for the faith [“the body of doctrine that was given by God through the apostles to the church” (Wiersbe)] that was once for all entrusted [to hand down, to commit, to deliver; cf. 1 Tim. 1:11; 6:20; 2 Tim. 2:2] to the saints [set-apart ones; to every believer].
4 For certain men [apostates: those who deliberately defected from God and opposed sound doctrine] whose condemnation was written about long ago have secretly [stealthily penetrated the church; reminder that we must remain doctrinaly alert and vigilant] slipped in [crept in unnoticed; they were already in the church; cf. 2 Pet. 2:1-2; gained entrance by pretending to be believers] among [along side of] you. They are godless [impious; have no respect or reverence for God; cf. 2 Tim. 3:5] men, who  change [to change into something else; to transpose (as a musician transposes a piece of music from a major to a minor key); connotation is that the false teachers were corrupting the grace of God] the grace of our God into a license [in order to justify their immoral behavior; they argue that Christians are free to do whatever they please because they have been freed from the law] for immorality [unbridled living; absence of moral restraint; cf. 2 Pet. 2:13-14,19] and  deny [to say no to] Jesus Christ our only [cf. Acts 4:12] Sovereign and Lord [beware of anyone who denies the deity of Christ].
Note: Sound doctrine is the best antidote to false doctrine. Do you know where you stand doctrinally? Can you readily spot error? Spotting error is the first step to confronting and correcting it.
Note: “The apostates of the Church are far more frequently the theme of the world’s talk than the thousands of good men and true who adorn the doctrine of God our Saviour in all things.” (C.H. Spurgeon)
5 Though you already know all this, I want to remind you [note three examples of apostasy; God judges apostates] that  the Lord delivered [to rescue, to save] his people out of Egypt, but later destroyed [to ruin] those who did not believe [and so the apostates would also die “in the wilderness of their unbelief” (Swindoll)].
6 And  the angels who did not keep their positions of authority but abandoned [to desert, to forsake] their own home—these he has kept [to keep in custody] in darkness [cf. 2 Pet. 2:4], bound with everlasting chains for judgment on the great Day [like the fallen angels, the apostates would “suffer God’s wrath in the coming day of judgment” (Swindoll)].
7  In a similar way, Sodom and Gomorrah and the surrounding towns gave themselves up to sexual immorality and perversion [homosexuality and perhaps beastiality, both condemned by God in Lev. 18:22-25]. They serve as an example [and warning to the ungodly] of those who suffer the punishment of eternal fire [like Sodom and Gomorrah’s citizens, the apostates would “face God’s fiery condemnation” (Swindoll)].
Note: Be careful about who you listen to. You cannot find the way of life in those who are spiritually dead.
8 In the very same way, these [false teachers] dreamers [those who imagine and speculate and form faulty opinions; those out of touch with reality] pollute [moral pollution] their own bodies, reject [do not recognize as valid] authority and slander [to revile, to blaspheme] celestial beings.
9 [illustration from the Assumption of Moses, an apocryphal book] But even the archangel Michael [considered by Jews to be the highest among the angels; in this illustration, Michael had been sent to bury the body of Moses], when he was disputing [to take issue] with the devil about the body of Moses, did not dare to bring a slanderous accusation against him [the wickedest of angels], but said, “The Lord rebuke you!”
10 Yet these men speak abusively [to speak evil, to blaspheme; cf. Ps. 73:9,11] against whatever [including doctrines of the faith] they do not understand [ignorance]; and what things they do understand by instinct, like unreasoning animals—these are the very things that destroy them.
11 Woe [an imprecation of doom; cf. 1 Cor. 9:16] to them!  They have taken the way [manner of life] of Cain [devoid of love; see Gen. 4:1-7; Heb. 11:4];  they have rushed for profit into Balaam’s [greedy for money; see Num. 22; Deut. 23:3-4; Neh. 13:2; 2 Pet. 2:15-16] error [wandering];  they have been [indicates their fate is already sealed] destroyed in Korah’s [insubordinate to leaders; a Levite who led a rebellion against Moses and Aaron; see Num. 16:1-33] rebellion.
12 These men [false teachers] are [cf. vv. 16,19] blemishes [spots or hidden rocks/reefs covered by water that destroy boats] at your love feasts [fellowship meals held in the homes], eating with you without the slightest qualm [without fear; with arrogance]—shepherds who feed [indulge; exploit the people for their own selfish ends] only themselves [cf. Ezek. 34:2]. They are clouds without rain [all show and no substance; nothing to offer those who thirst; cf. Prov. 25:14; hollow men with hollow teachings], blown along by the wind; autumn trees, without fruit [fruitless; nothing to offer those who hunger; cf. Matt. 7:16] and uprooted [rootless; contrast to godly man in Ps. 1:3]—twice dead [useless].
13 They are wild [untamed] waves of the sea, foaming up their shame [cf. Isa. 57:20]; wandering [or shooting] stars [produce no light; give no direction; quickly fade into the darkness; meteors], for whom blackest darkness has been reserved forever.
14 Enoch [cf. Gen. 5:18-24], the seventh from Adam, prophesied [quotation from Enoch 1:9 (an apocryphal book); the fact that Jude used this quote does not mean that the Book of Enoch was regarded as inspired or equal with Scripture] about these men: “See, the Lord is coming [personally] with thousands upon thousands of his holy ones [angels]
15 to judge everyone [universal judgment], and to convict all the ungodly of all the ungodly acts they have done in the ungodly way, and of all the harsh [rough, stern, uncivil] words ungodly sinners have spoken against him.”
16 These men are grumblers [those who murmur and complain] and faultfinders; they follow their own evil desires [lusts, passions]; they boast about themselves and flatter [exploit] others for their own advantage [profit, gain].
17 But, dear friends, remember what the apostles of our Lord Jesus Christ foretold [main test of truth in early church was to ask: Is this what the apostles taught?; they taught that apostates would come (cf. 1 Tim. 4; 2 Tim. 3; 1 Jn. 2:18ff; 4:1-6)].
18 They said [note five characteristics of the apostates] to you, “In the last times there will be  scoffers [mockers] who will  follow their own ungodly desires.”
19 These are the men who  divide [to make a distinction, to cause division] you, who  follow [without restraint or control] mere natural instincts [natural lusts and appetites] and  do not have the Spirit [bogus Christians (cf. Rom. 8:9); and therefore live without restraints].
20 But you, dear friends, build [edify; requires a study of the Scriptures and prayer] yourselves up in your most holy faith [cf. v. 3] and pray [an essential weapon in the battle against error] in the Holy Spirit.
Note: Someone said, “Prayer is not getting man’s will done in heaven—it is getting God’s will done on earth.”
21 Keep yourselves in God’s love [cf. Jn. 15:9b] as you wait [to earnestly expect] for the mercy of our Lord Jesus Christ to bring you to eternal life.
22 Be merciful [to show pity; patiently confront or convince] to those [those wounded by the apostates] who doubt [to waiver; the unstable; those not grounded in the faith];
23 snatch [requires quick action] others from the fire and save [rescue; cf. Jas. 5:19-20] them; to others show mercy, mixed with fear [with caution]—hating even the clothing [everything associated with the sin; this image probably taken from Lev. 13:47-59] stained by corrupted flesh.
24 To him who is able to keep you from falling [we must look to God for moral stability] and to present you before his glorious presence [before the face of] without fault [blame] and with great joy—
25 to the only God our Savior be glory, majesty [greatness, magnificence], power and authority, through Jesus Christ our Lord, before all ages, now and forevermore! Amen.