I think many atheists are not so much opposed to the idea of God as they are prone to thinking that God looks back at them in the mirror. While I am a fan of Rand I think she may have been in that camp.
Well... people WILL worship something. It can be self. That in fact was the Serpent’s original drawing card in the Garden temptation. Step up and get yer very own morality system here! Make God jealous! (Well, He was.)
But all manner of people may tell you they are atheists when really it’s a situation of finding they have a great difficulty attempting to exercise faith in God. Some of them pray!