What does Psalm 38:20 mean?

David's enemies were unscrupulous. They wanted to destroy David because he did what was good. They wanted to repay his honorable deeds with evil. Even if David had truly sinned (Psalm 38:18), their attacks went beyond anything reasonable (Psalm 38:19). Such enemies would have willingly lied about David before (Psalm 35:11–12), so they have no reason to reserve their criticism to something rational. Instead, they amplify their slander.

This is part of the fallen world's assault on godliness. When the ungodly fail to meet their already-low standards, they expect tolerance and refuse correction. On the other hand, when a self-identified believer falls short of perfection, the world is ready to pounce and magnify those mistakes (1 Peter 2:12).

John 3:19 declares: "And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil." God demonstrated the greatest good by giving His Son for the sins of the whole world (1 John 2:2), but the world demonstrated the greatest evil by crucifying God's Son. Jesus told His followers: "If the world hates you, know that it has hated me before it hated you. … because you are not of the world … the world hates you" (John 15:18–19). Proverbs 17:13 sounds a warning: "If anyone returns evil for good, evil will not depart from his house."