 “Fideism” is the name given to that school of thought – to which Tertullian himself is frequently said to have subscribed – which answers that faith is in some sense independent of, if not outright adversarial toward, reason. In contrast to the more rationalistic tradition of natural theology, with its arguments for the existence of God, fideism holds – or at any rate appears to hold (more on this caveat shortly) – that reason is unnecessary and inappropriate for the exercise and justification of religious belief. The term itself derives from fides, the Latin word for faith, and can be rendered literally as faith-ism. “Fideism” is thus to be understood not as a synonym for “religious belief,” but as denoting a particular philosophical account of faith’s appropriate jurisdiction vis-a-vis that of reason.