2 Peter 2:22
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. 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.
An outward or incomplete conversion does not keep a person from returning to a sinful life. When sin still seems pleasant and its pleasures have not been truly forsaken, temptation is yielded to and what was gained is lost.
The verse describes men who cause much trouble in the church by holding to their own opinions and refusing to give them up. They cherish and strengthen wrong ideas, regard their own judgment as infallible, and seek to spoil the church with their plans. They receive pleasing sophistries presented by deceiving angels and seek to make permanent theories that injure the Lord's work. In this course they follow Lucifer, who refused to alter his opinions and became unacceptable to God. The trouble such persons caused in the early church will be met again today, so all must be on guard.