Deism (/ˈdiː.ɪzəm/ or /ˈdeɪ.ɪzəm/, derived from the Latin word deus meaning "god") is a theological/philosophical position that combines the rejection of revelation and authority as a source of religious knowledge with the conclusion that reason and observation of the natural world are sufficient to determine the existence of a single creator of the universe.

Deism gained prominence among intellectuals during the Age of Enlightenment—especially in Britain, France, Germany and the United States—who, raised as Christians, believed in one god but became disenchanted with organized religion and notions such as the Trinity, Biblical inerrancy and the supernatural interpretation of events such as miracles. Included in those influenced by its ideas were leaders of the American and French Revolutions.