The Existence of God: Theories of Thomas Aquinas, St. Anselm, and William Paley The three readings that form the basis of this essay all deal with the existence of a God, something that which nothing greater can be conceived and cannot be conceived not to exist. The three readings include: Thomas Aquinas, St. Anselm, and William Paley. First let us start with Thomas Aquinas, a Dominican Monk (1225-1274) who is considered by many to be the greatest theologian in Western religion. Aquanis writes of two opposite theories with reasons for the non- existence of God and then for the existence of God. He starts off with his v