Natural theology is a branch of theology based on reason and ordinary experience. Thus it is distinguished from revealed theology (or revealed religion) which is based on scripture and religious experiences of various kinds; and also from transcendental theology, theology from a priori reasoning.

Marcus Terentius Varro (116-27 BC) in his (lost) Antiquitates rerum humanarum et divinarum established a distinction of three kinds of theology: civil (political) (theologia civilis), natural (physical) (theologia naturalis) and mythical (theologia mythica). The theologians of civil theology are "the people", asking how the gods relate to daily life and the state (imperial cult). The theologians of natural theology are the philosophers, asking for the nature of the gods, and the theologians of mythical theology are the poets, crafting mythology. The terminology entered Stoic tradition and is used by Augustine of Hippo.

Natural theology, thus, is that part of the philosophy of religion dealing with describing the nature of the gods, or, in monotheism, arguing for or against attributes or non-attributes of God, and especially the existence of God, purely philosophically, that is, without recourse to any special or supposedly supernatural revelation.