What does Jude 1:7 mean?

In this verse Jude presents another example of God's punishment of those who despise His laws and follow their sinful lusts. He mentions Sodom and Gomorrah and the surrounding towns. These urban sites existed in Abraham's lifetime and had a sordid history of sexual perversion (Genesis 13:13). Abraham's nephew Lot had been attracted to Sodom by the verdant pastureland surrounding the city (Genesis 13:10–11). At first, he settled near Sodom, but eventually moved into town, where he was "… greatly distressed by the sensual conduct of the wicked (for as that righteous man lived among them day after day, he was tormenting his righteous soul over their lawless deeds that he saw and heard)" (2 Peter 2:7–8). Ultimately God delivered Lot from Sodom but rained down burning sulfur on the perverse inhabitants of Sodom and Gomorrah and nearby towns (Genesis 19:24–25).

The punishment those wicked inhabitants received pictures the punishment that awaits false teachers. Just as the inhabitants of the earth had been exposed to Noah's preaching prior to the flood (2 Peter 2:5), even so the apostates of Jude's time had been exposed to the truth but had rejected it. Jesus had predicted that conditions similar to those in the days of Lot would exist prior to his return. Luke 17:26–29 records Jesus' prophecy: "Just as it was in the days of Noah, so will it be in the days of the Son of Man. They were eating and drinking and marrying and being given in marriage, until the day when Noah entered the ark, and the flood came and destroyed them all. Likewise, just as it was in the days of Lot—they were eating and drinking, buying and selling, planting and building, but on the day when Lot went out from Sodom, fire and sulfur rained from heaven and destroyed them all."