Execute Judgment On All

Read verse 15 aloud and you hear the repetition. Ungodly. Ungodly deeds. The ungodly way they committed them. The harsh things ungodly sinners have spoken against him. One root, four times, in a single sentence.
And notice the two things being judged. Deeds, and words. That is not incidental to Jude's letter - it is exactly the charge he brings in his own voice one verse later, where the false teachers are grumblers and malcontents whose mouths speak loud boasts.
The quotation is not decoration. He picked the verse that already described the people in front of him.
Scripture links:
- Jude 15 - "to execute judgment on all and to convict all the ungodly of all their deeds of ungodliness... and of all the harsh things ungodly sinners have spoken against him."
- Jude 16 - "These are grumblers, malcontents... loud-mouthed boasters."
Jude chose a quotation that indicts the mouth as well as the hands.