David declared, 

“The fool has said in his heart, ‘There is no God.’ They are corrupt, they have done abominable works, there is none who does good” (Psalms 14:1). 

Why is it foolish to deny the existence of God? For one thing, it reveals a person’s motive, which in this case, David says arose from a corrupt life, hence, the atheist does not want to give an account to God. Moreover, it is foolish because the evidence for a Creator literally surrounds and overwhelms us. The earth fits us perfectly as a home, and we fit perfectly into the environment of the earth, showing that we did not arrive by mere accident, but Someone created this place as a home, and created us to live here.