Charles H. Spurgeon on Psalms 14:4

"Have all the workers of iniquity no knowledge?" If men rightly knew God, his law, the evil of sin, the torment of hell, and other great truths, would they sin as they do? Or if they know these and yet continue in their iniquities, how guilty and foolish they are! Answer the question both positively and negatively, and it supplies material for a searching discourse.

Verse 4 (first clause). The crying sin of transgressing against light and knowledge.

Verse 4 (last clause). Absence of prayer, a sure mark of a graceless state.