 Philosophers and religious thinkers across almost every epoch and tradition (Near Eastern, African, Asian, and European) have engaged the project of natural theology, either as proponents or critics. The question of whether natural theology is a viable project is at the root of some of the deepest religious divisions: Shi’ite thinkers are optimistic about reason’s ability to prove various theological and ethical truths, for instance, while Sunnis are not; Roman Catholic theologians typically think that reason provides demonstrations of the existence of God, while many Protestant theologians do not. Unlike most of the topics discussed in an encyclopedia of philosophy, this is one over which wars have been fought and throats have been cut.