Peter now turns to danger inside the church. But false prophets also arose among the people, as false teachers will also be among you. They will secretly bring in destructive heresies, denying even the Master who bought them. Many will follow their immoral ways, and as a result, the way of the truth will be maligned. In covetousness they will exploit believers with deceptive words. Their judgment, Peter says, is not idle.
Peter supports this with three examples from Scripture. God did not spare angels when they sinned. He did not spare the ancient world, but preserved Noah with seven others when he brought the flood. He turned Sodom and Gomorrah to ashes, but delivered righteous Lot, who was distressed by the wickedness around him. The conclusion is a comfort: the Lord knows how to deliver the godly out of temptation, and to keep the unrighteous for the day of judgment.
The rest of the chapter describes the false teachers. They are daring and self-willed, and they speak evil of what they do not understand. They forsook the right way and followed the way of Balaam, who loved the wages of wrongdoing and was rebuked by a speechless donkey. These are wells without water, clouds driven by a storm. They promise liberty while they themselves are bondservants of corruption. Peter ends sadly: it would be better never to have known the way of righteousness than to turn back from the holy commandment.