Tritheism is an old religion that worships three deities: Horu the Sky God, Grattheos the Sea God and Maia the Earth Goddess. Hummel mentions that it predates the Hieroglyph Church. Tritheism is mainly practiced in the Orietta Region and northern Afroca.

Griselda points out that the religion is similar when she hears of the Three Principles mentioned in the monolith called the "Truth of Eternia". The Three Principles is the Eternian theory of the creation of the world through sky, sea and earth. Sahad thereafter theorized that Tritheism might have originated in Eternia.