Psalm 14

I am assuming that David's opening phrase refers to those Israelites who rejected God. Those who received the inheritence, who saw the fruit of Abraham's faith firsthand, who's ancestors were delivered from Egyptian slavery. I believe it was these people who repulsed David so much that he called them "fool." Since they rhad ejected God and his standards their actions reflected their lack of godly direction and none of them could do good. In spite of having access to the revealed word of God Almighty they did not seek after God.  I wonder if it was the thought of these foolish Israelites that motivated David to become a God chaser?
It took me less than 1 minute to read this psalm.
Stuart