The fool is a character who in Scripture is marked by wickedness as well as by what we call folly. His defect is moral as well as mental. In his heart] His denial is a practical one, and he really acts upon it, whatever he may say or think that he believes. There is no God] cp. Psalms 12:4; Psalms 11; Psalms 13.
Related Commentaries of Psalms 14:1
Psalms 14:1
1 The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good.