Adam Clarke on Psalms 14:4

Have all the workers of iniquity no knowledge? - Is there not one of them who takes this dreadful subject into consideration? To their deeply fallen state they add cruelty; they oppress and destroy the poor, without either interest or reason.

Who eat up my people as they eat bread - Ye make them an easy and unresisting prey. They have no power to oppose you, and therefore you destroy them. That this is the meaning of the expression, is plain from the speech of Joshua and Caleb relative to the Canaanites. Num 14:9 : "Neither fear ye the people or the land; for they are bread for us."

And call not upon the Lord - They have no defense, for they invoke not the Lord. They are all either atheists or idolaters.