The great Medieval theologian Thomas Aquinas believed it was possible to prove that God exists by reason alone (i.e., without relying on scripture or revelation) and he assembled 5 arguments which he believed did just that. He was not alone. Christian theologians like Anselm of Bec and philosophers like René Descartes and Gottfried Leibniz have been similarly confident. Medieval Muslim theologians including Avicenna (Ibn Sina) and Averroes (Ibn Rushd) came to similar conclusions as did the Medieval Jewish theologian Maimonides. John Hamer of Toronto Centre Place will outline some of the major arguments proposed by these figures and consider their merits.