Counterfeit Repentance (part 3)

The third deceit about repentance is the leaving of many sinful ways It is a great matter, I confess, to leave sin. So dear is sin to a man that he will rather part with a child than with a lust: `Shall I give the fruit of my body for the sin of my soul?' (Mic. 6.7). Sin may be parted with, yet without repentance.
(1) A man may part with some sins and keep others, as Herod reformed many things that were amiss but could not leave his incest.
(2) An old sin may be left in order to entertain a new, as you put off an old servant to take another. This is to exchange a sin. Sin may be exchanged and the heart remained unchanged. He who was a prodigal in his youth turns usurer in his old age. A slave is sold to a Jew; the Jew sells him to a Turk. Here the master is changed, but he is a slave still. So a man moves from one vice to another but remains a sinner still.
(3) A sin may be left not so much from strength of grace as from reasons of prudence. A man sees that though such a sin be for his pleasure, yet it is not for his interest. It will eclipse his credit, prejudice his health, impair his estate. Therefore, for prudential reasons, he dismisses it. True leaving of sin is when the acts of sin cease from the infusion of a principle of grace, as the air ceases to be dark from the infusion of light.

From The Doctrine of Repentance, by Thomas Watson.
Read part 1 and part 2.