Definitions on this topic is widely misunderstood, but here they are:
theism: from Greek theos belief in a supreme being.
atheism: a- (without) + theism; a lack of a belief in a supreme being.
antitheism: anti- (against or opposite of) + theism; a belief in the nonexistence of a supreme being.
agnosticism: a- + gnosis (knowledge); the belief that we cannot prove the existence of a supreme being.
ignosticism: (from ignore and agnosticism); the belief that the question of the existence of a supreme being has no verifiable consequence and thus it should be ignored.