“For if, after they have escaped the pollution of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning.  For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them.  But it has happened to them according to the true proverb: ‘A dog returns to his own vomit,’ and ‘a sow, having washed, to wallowing in the mire.’” (2 Peter 2:21-22 cf. Proverbs 26:11). 

The ones under consideration had “escaped the pollution of the world” (2 Peter 2:20 cf. 2:18).  They did so “through the knowledge of the Lord and Savior Jesus Christ” (2 Peter 2:20, cf. “error” 2:18).  The word “know” appears in some form 16 times in the book of 2 Peter [(1) Knowledge (1:2, 3, 5, 6, 8; 2:20; 3:18) (2) Know(s) (1:12, 2:9; 3:17); (3) Knowing (1:14, 20; 3:3); (4) Known (1:16; 2:21 x 2)] Knowledge is part of the ingredient for spiritual success (2 Peter 1:5-11). 

What if these do not continue to live as Christians?  What if “they are again entangled” and “overcome”?  What if they “turn from the holy commandment delivered to them?  Peter writes: (1) “The latter end is worse for them than the beginning” (2 Peter 2:20).  (2) It would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment” (2 Peter 2:21). 

What does this mean?  (1) This may refer to the fact that it is very difficult to regain those who willfully choose to leave the way of righteousness (cf. Hebrews 6:4-6).  (2) This may refer to greater knowledge leading to greater expectations, and possibly greater severity in judgment (Luke 12:42-48; Hebrews 10:26-29).

In order to show how disgusting it is to turn back, Peter used two proverbs.  (1) He refers to a dog that returns to its own vomit (2 Peter 2:22 cf. Proverbs 26:11).  (2) He refers to a sow (female pig) that has been washed returning to the mire.  This second proverb does not appear earlier in scripture.  However, it was probably a well-known saying in Peter’s day.  Adam Clarke cites a Jewish midrash (commentary) which says, “Orphah is returned to her mire, Ruth persevered in spirit.”

Some have missed the point.  They suggest that the dog and pig were never changed in nature (Calvinism).  This is why they returned to the vomit and mire.

However, this is not the point of the text.  It is not about their unchanged nature.  It is about the forsaking of the right way (notice: 2 Peter 2:1-2, 15, 21).  Guy N. Woods comments, “The dog has ejected that which was foul; the sow had been washed.”  However, both returned to the filth.  May we never return to the filth.