2 Peter 2:20-22

For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning. For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them. But it is happened unto them according to the true proverb, The dog is turned to his own vomit again…
…and the sow that was washed to her wallowing in the mire.

Peter does not dress this up. He reaches for two painfully vivid pictures, a dog and a pig. Why? Because false teaching is not merely mistaken. It reveals nature. It shows what a person really loves when all the polish wears off.

The dog returns to what made him sick.

The pig returns to what makes her dirty.

Peter says that is what happens when people turn from the holy commandment delivered to them. They may have escaped certain pollutions outwardly. They may have learned the language of righteousness. They may have moved around Christian truth for a season. But if there has been no real change of heart, they eventually go back to what matches their nature.

That is why Peter’s warning is so sharp. He is not describing a simple stumble in the life of a believer. He is describing people who traffic in truth and then turn from it, who handle holy things and then go back to corruption, who wear religion for a while but are finally drawn back to what they truly love.

And Peter gives us two common forms of that corruption.

First, there are the dogs of legalism. These are the people who say, “Simple faith in Jesus is not enough. You need Christ plus pain. Christ plus rules. Christ plus our system. Christ plus our burden.” They love to add to the gospel because misery feels spiritual to them. They make holiness sound like a joyless prison, and then they try to lock everyone else inside with them.

Notice this. Legalism usually grows in the soil of unhappiness. A miserable man often wants company. If he feels bound, he wants you bound too. If he is under law, he wants you there with him. So he barks and snaps and warns and scolds. But Peter says watch long enough, and you will often see something revealing. The very people who preach hardest against grace often end up falling back into the very sins or tendencies they denounce most loudly.

That is the dog returning.

Then there are the hogs of hedonism. These are not adding burdens. They are removing boundaries. They say liberty means indulgence. Freedom means pleasure. Truth means little so long as desire is satisfied. They may clean themselves up for a while. They may look presentable. They may even sound persuasive. But give it time, and back they go to the mud.

That is the pig returning.

You need to see this. Legalism and hedonism look opposite, but they are cousins. Both are flesh driven. One finds pleasure in control. The other finds pleasure in indulgence. One says, “Touch not, taste not, handle not.” The other says, “Touch everything, taste everything, indulge everything.” But neither one is the liberty of Christ.

Real liberty does not drive a man back to vomit or mud.

Real liberty makes a man love Jesus.

That is why Peter’s warning lands so powerfully. False teaching may wear a strict face or a loose face. It may come sounding severe or sounding permissive. But if it pulls people away from the sufficiency of Christ, the grace of the gospel, and the holiness that comes from a changed heart, it is false all the same.

And there is a personal warning here too. Peter is not only helping us identify false teachers out there. He is helping us recognize the tendencies that can still try to rise within us. There is a little legalist in the flesh. There is a little pig in the flesh. One part wants to take pride in rules. Another part wants to run to the mud. Both must be brought to the Cross.

Saints, stay close to Jesus. Do not add to His gospel. Do not turn His liberty into license. The answer is not law on one side or lust on the other. The answer is a new nature, a cleansed heart, and a life that keeps abiding in the One who truly sets men free.