22 But it has happened to them according to the true proverb: “A dog returns to his own vomit,” and, “a sow, having washed, to her wallowing in the mire.”
The New King James Version (Nashville: Thomas Nelson, 1982), 2 Pe 2:22.
Just to help with context, Peter is speaking of false teachers and prophets, warning the church that many will follow their destructive ways. Nevertheless, destructions awaits them according to the will of God.
These false teachers exist today. They appear in almost every way to be part of the body of Christ. They do the work of the church, they speak the church language and they hold esteemed church positions. The eye test says they are part of the body of Christ. Fortunately God sees through all of that and recognizes them for what they are and to whom they truly belong.
Then comes life. Life does not descriminate. Matthew says in chapter 5 verse 45 “that you may be sons of your Father in heaven; for He makes His sun rise on the evil and on the good, and sends rain on the just and on the unjust.” Christians are called to endure life’s circumstances and stand firm on Jesus Christ. God equips His children to do this through the indwelling of the Holy Spirit. Not so with false teachers and false Christians. Aside from sheer will power, they have no way to endure the test of time and circumstances. They have no foundation to stand on (Jesus) and no Spirit to live from (Holy Spirit). They eventually fold under the pressure and their true identity is revealed. In the end they never were what they seemed to be and soon return to what they had been all along.