What does Psalm 36:3 mean?
David is depicting the attitude of a depraved person who rejects God and embraces sin (Psalm 36:1–2). Earlier verses suggested self-deception, as the wicked person assumes they will suffer no consequences for what they do. Here, the evil individual themselves is a source of lies and deceptions (Proverbs 6:16–19; Psalm 7:14).This pattern follows the example of Satan. Ephesians 2:1–2 describes the life of believers before they trusted in Christ as their Savior. It says when they were "dead in the trespasses and sins," they "walked, following the [evil world system], following the prince of the power of the air [the Devil], the spirit that is now at work in the sons of disobedience." Jesus spoke of the link that exists between a corrupt heart and corrupt words and deeds. He said, "You brood of vipers! How can you speak good, when you are evil? For out of the abundance of the heart the mouth speak…the evil person out of his evil treasure brings forth evil" (Matthew 12:34–35).
This verse also notes that the wicked person acts foolishly. It is extremely unwise to disobey God by leading a sinful life (Proverbs 1:7; 3:1–6; 8:34–36).