atheism is a person who doesn't believe in the existence of a god. just because top G has no one to look up to, doesn't mean that he's an atheist because by definition you have to not believe in a divine deity's existence. in layman's terms, God believes in himself [he knows he is real because hes him lol]
I can tell you, God is absolutely, positively, an atheist. And his angels are not religious either. They just believe in good and order amongst living things with a conscience. Everything else, was made up by people.
not to be that guy that quotes a bible verse as his "silver bullet" but in revelations 7:11 the angels "fell down on their faces before the throne and worshiped God, saying, 'amen! praise and glory and wisdom and thanks and honor and power and strength be to our God for ever and ever.'