Classical theism is the form of theism in which God is characterized as the singular Absolute Being, Absolute Self, and Ultimate Person who is the source and origin of all the other beings.

Theism is broadly defined as the belief in the existence of at least one deity. In common parlance, or when contrasted with deism, the term often describes the philosophical conception of God that is found in classical theism—or conception found in monotheism—or gods found in polytheistic religions—or a belief in God or gods without the rejection of revelation as is characteristic of deism.