Jude Quotes Non-Canonical Texts

The argument usually stops at the wrong question. People ask: was 1 Enoch inspired? Heiser says the canonicity question is secondary, and asks a different one - did the New Testament writers know this book, use it, and expect their readers to recognise it?
On that question the evidence is not thin. Jude quotes 1 Enoch 1:9 almost in full. Second Peter uses the language of 1 Enoch 10 verbatim - chains of gloomy darkness, kept until judgment. Revelation's lake of fire draws conceptually on 1 Enoch 10-21. Matthew 25:41 speaks of fire prepared for the devil and his angels.
None of that makes 1 Enoch Scripture. All of it means the apostles were writing to people who had read it.
Scripture links:
- Jude 14-15 - The direct quotation.
- 2 Peter 2:4 - "chains of gloomy darkness... kept until the judgment."
You do not have to accept a book as Scripture to admit the apostles expected you to have read it.