The Epistle of St. Jude is Enochic Literature - Here's Why
(This is cribbing a lot from Fr. Stephen DeYoung's article "The Book of Enoch", so read that - also, it's really good).
The Epistle of St. Jude is a very short and pretty minor book of the New Testament - it's one chapter, read it here. The Enochic tradition was a literary corpus written between the 3rd and 1st centuries BC, centred on the First Book of Enoch but including other texts such as the Book of Jubilees and the Book of Giants, with unifying themes such as having the character of Enoch from Genesis as a central figure, the Enochic calendar (a particular way of organising the Jewish calendar), an apocalyptic emphasis, detailed angelic hierarchies (in particular assigning governing angels to different parts of the world) and ascribing human sin to rebellious angels.
So, the point of this post is that the Epistle of St. Jude represents a Christianised version of Enochic literature. This can be seen in four points:
v.6: "And the angels who did not stay within their own position of authority, but left their proper dwelling, He has kept in eternal chains under gloomy darkness until the judgment of the great day—". This represents a very truncated version of the Watcher story. In it, several angels are assigned to watch over humanity in its infancy, but rebel and corrupt it by fathering giants with mortal women and teaching sorcery and other forbidden knowledge to humans; God imprisons the watchers in the abyss and wipes out the giants via the Flood. The story, while not found (at least not explicitly) in Genesis, was a favourite theme of the Enochic tradition - it's the central theme of the Book of the Watchers, the largest and most famous part of the First Book of Enoch, the main topic of the Book of Giants and appears in the Book of Jubilees. While you could argue that St. Jude got this from the Nephilim story in Genesis 6:1-4, that story doesn't include the detail that the rebellious angels were "kept in eternal chains under gloomy darkness"; he could only have gotten that from the Enochic tradition.
v.9: "But when the archangel Michael, contending with the Devil, was disputing about the body of Moses, he did not presume to pronounce a blasphemous judgment, but said, “The Lord rebuke you.”" In the Enochic tradition, Michael is the opponent of Satan in God's jury, with Satan acting as the "lawyer for the prosecution" and St. Michael as the "lawyer for the defence". While this conception of Satan appears in the Book of Job, and St. Michael first appears in the Book of Daniel, the Enochic tradition was the first to make much of pairing them up, as seen in the First Book of Enoch.
v.14a: "It was also about these that Enoch, the seventh from Adam, prophesied, saying". Firstly, this calls Enoch a prophet, which heavily implies that St. Jude thought 1 Enoch was at least partly divinely inspired. Secondly, "the seventh from Adam" is a title derived from the First Book of Enoch.
v.14b-15: "Behold, the Lord comes with ten thousands of his holy ones, 1to execute judgment on all and to convict all the ungodly of all their deeds of ungodliness that they have committed in such an ungodly way, and of all the harsh things that ungodly sinners have spoken against him." This is a quote from the Book of Enoch, specifically 1 Enoch 1:9.
Notably, these all come from the section marked in English Bibles as "Judgement on False Teachers" or something similar, made up of verses 3 to 16 - fourteen verses in a twenty-five verse book. Sine this section is permeated with Enochic ideas and terms, and is the bulk of the letter, I'd go so far as to call St. Jude's Epistle an Enochic book.
