Dualism in cosmology or dualistic cosmology is the moral or spiritual belief that two fundamental concepts exist, which often oppose each other. It is an umbrella term that covers a diversity of views from various religions, including both traditional religions and scriptural religions.

In the Platonic, Neopythagorean, Middle Platonic, and Neoplatonic schools of philosophy, the demiurge is an artisan-like figure responsible for fashioning and maintaining the physical universe. The Gnostics adopted the term demiurge. Although a fashioner, the demiurge is not necessarily the same as the creator figure in the monotheistic sense, because the demiurge itself and the material from which the demiurge fashions the universe are both considered consequences of something else. Depending on the system, they may be considered either uncreated and eternal or the product of some other entity.