Thomas Aquinas, on Ps 52:1

“Unto the end, for Maeleth, understandings to David. The fool said in his heart: There is no God.”

“"They are corrupt." Here is the effect of their malice. Just as fear, knowledge, and love of God is the principle of every good work, so when knowledge and love of God are removed, all good life is taken away. And first he shows what follows as to the doing of evil; second, as to the loss of good. There are two evils that follow. The first is that "they are corrupt." The body is corrupted through the evaporation of natural heat and through the withdrawal of actual exterior heat. The natural heat of the human soul is God himself; and therefore, as long as knowledge of God is in the soul, the soul retains its form which God impressed upon it, namely innocence and the divine image; but when this heat evaporates and actual heat is withdrawn -- namely the heat of concupiscence and of fear -- the soul is corrupted, and consequently it follows that many cast off fear and love and the knowledge of God from themselves and are corrupted in impurities; and therefore "they have become abominable in their iniquities." Hos. 9: "They became abominable like the things they loved." And he says "iniquity," that is, on account of their iniquities, and they also lose what is good. "There is not one who does good." Jer. 4: "They are wise to do evil, but to do good they have no knowledge."”

Imported from an open dataset — not yet checked against the printed edition.