Pyro7480:
That is because the Letter of St. Jude cites from 2 Non-canonical sources, the “Assumption of Moses”, which is where verse 9 that you cite comes from and it also cites 1 Enoch in vv 14-15.
So if citation of a book is the principle for canonicity, which the Original article linked by the OP, Gamecock, argues is a key principle of Protestant OT Canon determination, then why did the Protestants not include these books and keep the books of Joshua, Judges, Ruth, 1 Kings, 1 Chronicles, 2 Chronicles, Ezra, Nehemiah, Esther, Eccelesiates, Song of Solomon, Lamentations, Obadiah, Nahum and Zephaniah, as “None” of these books are quoted in the New Testament.
Thus, the principle of canonicity, i.e. “OT book being quoted in the NT” is baseless. Protestants can kick scream, yell, bury their heads in the sand all they want, but the bottom line is the Catholic Church’s 73 Book Canon [46 OT and 27 NT] is grounded the decisions of the 4th//early 5th century at Rome 382 AD, Hippo 393 AD, Carthage III 397 AD, and St. Augustines Letter 396/397 AD and Pope Innocent I’s Letter in 405 AD followed by Carthage IV in 419 AD. Thus, the Councils at Florence in 1442 and once again at Trent in 1563 and the decrees regarding the Canon, once again, the same 73 Book Canon, is the dominant Tradition of Western Christendom and thus the “Protestant” decision to remove the 7 Deuterocanonicals is the anomaly and novel position in Christianity. Period, End of Discussion!
Thank you.