The writer of this Epistle identifies himself in the opening statement as Judas, a brother of James (1:1). No doubt he was well known and needed no further identification. Really out of the seven men named Yoúdahs in the New Testament, there are only two possibilities: Judas also called Thahddaíohs, the son of Ahlfaíohs, a disciple of The Lord Jesus (Lk. 6:15,16 cf. Mk. 3:18; Jn 14:22; Acts 1:14); and Yoúdahs (Jude), the half brother of our Lord Jesus Christ (Mt. 13:55; Mk. 6:3;). It is not likely that the son of Ahlfaíohs, is the writer because there is no indication in Acts or elsewhere in the New Testament that he had an outstanding leadership ministry in the church as did the half brother of Jesus. So the writer has been generally accepted as the half brother of the Lord Jesus Christ and full brother of James, who presided over the first church council at Jerusalem (Acts 15:13 cf. Gal. 1:18,19; 2:9,12), performed a leading roll (called a pillar of the church by Paul, Gal. 2:9) in the direction the church was to take, and wrote a Catholic (general) Epistle bearing his name, which Epistle was included in the Canon of Scripture (James 1:1).
The readers of this Epistle were predominately Hebrew Christians of Palestine. This destination is deduced by the Jewish tone of the Epistle and tradition that the descendants of Yoúdahs resided there.
Internal evidence is limited to the opening salutation by Jude (1:1) and the accepted title that bears his name, which was placed at ‘the head of the scroll' of the circulated copies.
External evidence comes from the writings of the church father, Origen (A.D. 185-254), "Jude wrote an Epistle of a few lines, but one filled with strong words of heavenly grace"; and The Muratorian Canon (A.D. 160-200), "The Epistle of Jude indeed, and . . . are accepted in the Catholic Church."
The purpose of Jude is to entreat Christians to earnestly contend (intensely agonize in struggle) "for the faith" and to warn against apostates and their acts, and against religious libertines who creep in unawares. "The faith" is the whole body of truth, a deposit of what and to which early Christians committed their trust. An apostate is one who has been exposed to the truth of the Gospel and has given at least intellectual assent to the faith of Christ, but has turned away to immorality or some ethical religion or faith. And in heart he has refused both to repent and to acknowledge the need of both repentance and committed trust to Christ's saving work at Calvary. Apostasy is when man turns the grace of The God into lasciviousness and claims, " because I am in Christ, I can live the way I want."
Yoúdahs or Jude gives examples of apostasy, three examples each of groups and of individuals.