God never acknowledges the existence of atheists in the bible. He only says, "The fool has said in his heart, there is no God."
Nor does he acknowledge the platypus. They're fakin' it too I suppose, just a duck in a brown coat?
Anyway - I believe that you will find the very psalm you are quoting is talking about atheists.
It doesn't say "The fool has lied loudly with his mouth, saying there is no God", but rather "(he) has said in his heart".
Sounds to me like "the fool" in this verse truly believes there is no god... Or do you "say things in your heart" that you think are false? I don't.
Someone who truly believes "there is no God", is an atheist, no?