We do not know he was quoting the Book of Enoch. Calvin and Gill are of the opinion that Jude was quoting from a saying perserved in ancient tradition as an authentic saying of Enoch, held in high regard by the Jews of his day. Note Jude does not say, "Enoch wrote...", but "Enoch...prophesied..."

And then, as Bryan notes above, even if he were quoting the apocryphal (non-canonical) Book of Enoch, that in no way validates the remainder of the book, for Paul also quotes or alludes to non-Biblical writers (cf Acts 17:28 and Titus 1:12) without authenticating their works.

In my view, it is doubtful Jude was quoting the book, so filled with rubbish as it is.

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Steve Rafalsky
Elder, International Evangelical Church (Reformed)
Limassol, Cyprus

"I am set for the defense of the gospel" (Philippians 1:17)

"Strengthened with all might, according to His glorious
power, unto all patience and longsuffering with joyfulness..." (Colossians 1:11)

Blog: A Great and Terrible Love