When I was very young, my family lived in a village. My mother reared a few hens and ducks which she slaughtered for Chinese New Year. We had a rich uncle whose children wanted a piglet for a pet. So they bought a piglet and asked my mother to look after it. This piglet was kept in an enclosure, and my mother kept it very clean at all times. It was the cleanest pig in the whole village.

Of course, that is not the normal state of pigs. The proverb that Peter cites in 2 Peter 2:22 describes the true nature of pigs: ″A sow that is washed returns to her wallowing in the mud.″ A sow which has been washed will not remain clean for long. It will return to the mud to roll in it again. Similarly, a dog will not walk away from its own vomit, but will go back to sniff around it (2 Peter 2:22).

These two proverbs describe the state of the false teachers. They had ″escaped the corruption of the world by knowing our Lord and Saviour Jesus Christ″ (v. 20); this describes their conversion, when their knowledge of Jesus Christ meant that they had escaped the corruption caused by evil desires (1:3-4). For these people to have known our Lord and Saviour Jesus Christ and the way of righteousness, and then to turn their back on Christ and all of Christ's teachings, it will be worse than not having known Jesus (2:21). They are like the dog that returns to its vomit, and the sow that returns to wallow in the mud (v. 22).

This is a clear warning to the false teachers that their final judgment is certain. Peter has already spoken of their destiny: their condemnation hangs over them (v. 3), and swift destruction will come upon them (v. 1). They will be punished on the day of judgment (v. 9) and what awaits them is ″blackest darkness″ (v. 17). This is the destiny of these false teachers who knew Christ and His teachings but have turned their backs on Him and His grace.

This is also a warning to new Christians not to follow the false teachers, or they will come to the same end. New believers must continue to grow in their knowledge of our Lord and Saviour Jesus Christ; they must take hold of God's promises so that they will not return to the corruption of the world from which they have escaped (1:3-4).