Peter uses Jude 1:7 as his source for this verse, though he makes some changes to the text of Jude. Again, as with the messengers or angels his focus is not on the sins of these cities but their judgment which serves as a prototype of future judgment. Biblically, the cities of Sodom and Gomorrah are remembered for the gravity of their sin (Genesis 18:20) and their cataclysmic judgment by fire (Genesis 19:12–29). The prototypical motif of destruction by fire became an illustration of divine judgment (Deuteronomy 29:22–24; Isaiah 34:8–10; Ezekiel 38:21–23; Amos 1:3 – 2:3); the destruction of Jericho (Joshua 6:24) and Gibeah (Judges 20:36–40) also echoing the Sodom and Gomorrah story.1 Though we are not specifically told that the cities burned to ashes, that is a fair assumption given that fire levelled the cities (Genesis 19:23–29).2 In short, God’s past judgments against people who embrace a life of sinfulness, especially when it is to the detriment of others, should lead people to change their ways.
6 if by turning the cities of Sodom and Gomorrah to ashes he condemned them to extinction, making them an example of what is going to happen to the ungodly;