20 If they have escaped the corruption of the world by knowing our Lord and Savior Jesus Christ and are again entangled in it and are overcome, they are worse off at the end than they were at the beginning. 21 It would have been better for them not to have known the way of righteousness, than to have known it and then to turn their backs on the sacred command that was passed on to them. 22 Of them the proverbs are true: “A dog returns to its vomit,” and, “A sow that is washed returns to her wallowing in the mud.” (2 Peter 2:20-22)
In 2 Peter 2:20-21 we discover that if a person "outwardly" starts down the road of the Christian life, escaping from the defilements of the world, and he turns away from the Lord, he probably wasn't a follower of Christ in the first place.
This underscores a very important principle: a sign that we have been born again and come into a personal relationship with God is that we persevere in the faith. On the other hand, the more we know of the reality of Christ, the more severe our judgment.
Now, Peter is not teaching that we could lose our salvation. He is teaching that people who make outward professions of faith and even begin to clean up their lives can turn away from Christ and be lost. In fact, in v.22 he explains we should not be overly surprised at this: dogs characteristically return to their vomit; and no matter how clean you make a pig on the outside, if it is still a pig, it will return to the mud.
In biblical times dogs were very rarely kept as household pets. They were used sometimes to herd sheep. They were dirty, greedy, snarling, often diseased and vicious, dangerous and despised. And they were just as likely to eat their own vomit as anything else. The Jews treated dogs with contempt because of their filth. They lived on garbage. They carried disease. They ate the garbage and then returned to eat what the garbage produced in them, filthy creatures, filthy creatures.
These false teachers had reformation, but not salvation. Their problem was they had turned to Christianity but they had not turned to Jesus! This is the story of Judas and it underscores that being saved and being moral are not one in the same. Judas was probably the most buttoned up of all of the disciples, yet he lacked a personal relationship with the Lord.
