Agnosticism is not a religion, but a philosophy. It is about the belief of the existence of a God or Goddesses.
Agnositics belive that God's existence can neither be proven or disproved. Since they do not believe in God, they are not Theists; since they are not certain that God does not exist, they are no Atheists. An agnostic usually holds these questions open, pending more evidence. They are willing to change their belief if some solid evidence or logical proof is found in the future.
George Smith, the author of "Atheism" divides agnostics into two types: