David's hatred did not bring anyone salvation. Sometimes it's easy to lose sight of the fact that Psalm 139:20 applied as much to us as to anyone else:
Ephesians 2:3
Among them we too all formerly lived in the lusts of our flesh, indulging the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest.
Colossians 1:21
And although you were formerly alienated and hostile in mind, engaged in evil deeds,
Romans 5:10
For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life.
Fortunately for us, God is love (1 John 4:8), not hate:
Ephesians 2:3-4
But God, who is rich in mercy, because of His great love with which He loved us, even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved),