Most readers notice the connection between Jude 6 and 2 Peter 2.4, but the similarities go beyond that. Second Peter has a lot more material in between some of the parallels, but the two epistles actually touch on much of the same subject matter, in the same order:
- Jude 1 = 2 Peter 1.2
- Jude 4-5 = 2 Peter 2.1
- Jude 6-10 = 2 Peter 2.4-12
- Jude 12-13 = 2 Peter 2.17
- Jude 17-18 = 2 Peter 3.1-3
- Jude 20-23 = 2 Peter 3.11-12
- Jude 25 = 2 Peter 3.18
I think the key point in helping determine which came first, Jude or 2 Peter, lies in Jude's attribution of a quote to Enoch, in Jude 14-15. This is universally recognized to be a direct quotation from the apocryphal book 1 Enoch, verse 1.9.
What is less noticed is that Jude shares several key words and phrases with the Greek version of 1 Enoch, and further thematic parallels with the Aramaic and Ge'ez versions of 1 Enoch.
1 Enoch 1.8: verbal parallels of 'called /select' (κλητοις /εκλετους), 'kept /belong' (τετηρημενοις /συντηρησει), 'mercy' (ελεος), and 'peace' (ειρηνη)
1 Enoch 1.9: verbal parallels of 'judgment' (κριμα), and 'irreverent' (ασεβεις)
1 Enoch 48.10: verbal parallels of 'deny', 'Lord', and 'Christ/Messiah'
1 Enoch 67.10: verbal parallels of 'judgment', 'deny', and 'Christ/Messiah', and thematic parallel of sexual sin ('perverted into sensuality' in Jude, 'the lust of their flesh' in 1 Enoch)
1 Enoch 10.4-6: verbal parallels of 'chains /bind' (δεσμοις /δησον), 'gloomy darkness /darkness' (ζοφον /σκοτος), and 'the great day of judgment /the day of great judgment' (κρισιν μεγαλης ημερας /τη ημερα της μεγαλης της κρισεως), and thematic parallel of angels being punished by fire
1 Enoch 12.4: verbal parallel of 'abandoned' (απολιποντας /απολιποντες), and thematic parallels of angels leaving heaven, and committing sexual sin
1 Enoch 70.8: contain the unique identification of Enoch as 'the seventh from Adam'
1 Enoch 1.9: a direct quotation from 1 Enoch, with only minor verbal differences
While books with similar subject matter may be expected to use similar vocabulary, textual criticism highlights when such similarities are too overt and highly-concentrated to have been written by mere coincidence. And given that Jude specifically names his source as 1 Enoch, offering a direct quote from the apocryphal book, it becomes clear that the epistle of Jude borrowed extensively from 1 Enoch.
We notice that most of the parallels between Jude and 1 Enoch occur in the sections where there are parallels between Jude and 2 Peter. However, 2 Peter does not contain the direct quotation from 1 Enoch 1.9 that Jude 14-15 has, and lacks several of the other verbal parallels Jude has with 1 Enoch.
For example, while Jude 1 and 1 Enoch 1.8 and 2 Peter 1.2 all three share the word 'peace', 2 Peter lacks the words 'mercy', 'called /select', or 'kept /belong' as shared by Jude and 1 Enoch. Or another example, while Jude 4 and 1 Enoch 48.10 and 2 Peter 2.1 all three share the verb 'deny', 2 Peter lacks the words 'Lord' and 'Christ/Messiah' as shared by Jude and 1 Enoch; instead, 2 Peter 2.1 keeps the word 'Master', also found in Jude 4.
The parallels with Jude and 1 Enoch are clear, and the parallels with Jude and 2 Peter are clear, and several of those parallels directly overlap. But the parallels between 2 Peter and 1 Enoch are very vague and indirect. If we assume 2 Peter came first and purposely diluted his references to 1 Enoch, we would have to then assume something rather unlikely: that Jude borrowed from 2 Peter, noticed that 2 Peter scrubbed out all direct references to 1 Enoch, and then restored them.
A far more likely scenario has 2 Peter's hazy verbal and thematic parallels with 1 Enoch explained by 2 Peter being one-stepped removed from the apocryphal book, that 2 Peter was borrowing from 1 Enoch indirectly. The author of Jude made extensive use of 1 Enoch, so that the whole epistle is permeated by Enochic language and ideas. Then the author of 2 Peter borrowed from Jude, adding new material and altering the original Enochic sections to suit his purposes.
Jude came first.