The contrast in this psalm is not only between good and evil, but more specifically between the prideful man who lives without fear of God and the God in whom godly men trust.
The description of the evil man (vv. 1-4) is an apt description of a modern-day humanist. He is convinced that God, if He exists, does not intervene in the affairs of men. He therefore sets himself up as an authority, deciding right and wrong on his own arbitrary scale. He has "no fear of God" (v. 1), and arrogantly he "flattereth himself in his own eyes" (v. 2), speaking "iniquity and deceit" (v. 3). He is foolish, and even his humanitarian deeds are not good, in the ultimate sense. Furthermore, the modern-day humanist "abhorreth not evil" (v. 4), insisting that such sins as promiscuity, homosexuality, witchcraft, abortion, brainwashing of children in pantheistic evolution, etc., are, in reality, to be desired.
The contrast with God consists of a list of some of His majestic attributes in His dealing with men. "Thy mercy, O Lord, is in the heavens; and thy faithfulness reacheth unto the clouds. Thy righteousness is like the great mountains; thy judgments are a great deep: O Lord, thou preservest man and beast. How excellent is thy lovingkindness, O God! therefore the children of men put their trust under the shadow of thy wings. They shall be abundantly satisfied with the fatness of thy house; and thou shalt make them drink of the river of thy pleasures. For with thee is the fountain of life: in thy light shall we see light" (vv. 5-9).
The wicked with his "foot of pride" will ultimately fall (vv. 11-12). But we can pray as David prayed, "O continue thy lovingkindness unto them that know thee; and thy righteousness to the upright in heart" (v. 10). JDM