If belief or a believing mind is necessary in order to make all truth and reality known to everyone. And it is impossible for atheism being a unbelief to exist in reality, because belief and a believing mind is necessary in order to make reality known. And whereas atheism is just a unbelief and a unbelieving mind and not a belief or believing mind, then thinking as atheists do that they can believe a unbelief like atheism exists in reality is a delusion.