Theism is the belief in definite articles. It is seperated into two distinct branches: monotheism - the belief in a single definite article ("the The and only one The"), and polytheism - the belief in the existence of more than one definite article (polytheism is more common in places like France, where theism is know as "leisme", and Spain, where it is known as "elismo").
Aism, the belief in indefinite articles, is the opposite of theism.
Atheism is the belief in both definite and indefinite articles.
This is why I have decided that I am an atheist. Religion has never been more grammatically correct.