godless: giving God none of the reverence he is owed, and living with no regard for his claim
Greek built this word by putting "not" in front of the family of words for reverence and worship. It is not a statement about what someone believes. It names what someone withholds: no awe, no worship, no reckoning with God at all. In the wider Greek world that counted as a public offense rather than a private opinion, and the Greek Old Testament took the word over to name the person who lives outside any regard for the God of Israel, the settled opposite of the person who is in the right with him.
In Peter and Jude the word is a verdict already passed, and every time the sentence around it is looking toward judgment.
- the world of the flood, swept away while Noah and seven others were kept safe
- Sodom and Gomorrah burned to ashes and set up as a warning of what is coming
- the present sky and earth, stored up for a day of judgment and ruin
- the people who slipped quietly into the churches, twisting God's kindness into a license to do as they pleased
Paul turns the same word the other way round and makes it the description of the person God rescues. God is the one who declares the godless to be in the right, and Christ died for the godless while they were still helpless. The shock is deliberate: Israel's own law told a judge never to acquit the guilty, and Paul uses of God the very word that law had used. The two ways of using the word do not disagree about what it means. Both assume this is the person with nothing to plead. They differ only over what God decides to do about that.
Jude stacks the whole word family into one sentence, convicting the godless of the godless things they did in a godless way, and adds the matching noun for the condition itself (ἀσέβεια). The repetition adds no new information, only weight, and that is the point: the word does not label one bad act but a whole way of standing toward God.