Psalm 14:1 - "The fool has said in his heart, 'There is no God.' They are corrupt, they have committed abominable deeds; there is no one who does good."
It is one thing to be foolish. It is quite another to be a fool. We all think and behave foolishly at times. However, to allow our minds to think foolishly over a lifetime creates the life of a fool. Just because we have gone fishing a time or two does not mean for our epitaph they will say that we were a fisherman. That would be abusrd! When we fill our lives with a certain hobby or work or even faith, then we will be known for what we have practiced.
To deny God takes faith just as to believe in Him similarly takes belief. Atheists do not like to confess that they cannot prove that God does not exist. Therefore, they must use faith for their hypotheses regarding how and why we are here. The leap of faith becomes even more profound for those who have become fools in their own thinking, because they have nothing to witness to their beliefs other than their own flawed logic.
Believers have not only the irrepressible witness in nature but also the inner witness of God when He causes us to be born again. An argument cannot be won when a child states to an atheistic professor that "they know that they know that they know that God dwells within them." For heavenly wisdom such as this, there is no human logic.