Binitarianism is a Christian theology of two persons, personas, or aspects in one substance/Divinity (or God). Classically, binitarianism is understood as a form of monotheism—that is, that God is absolutely one being—and yet with binitarianism there is a "twoness" in God, which means one God family. The other common forms of monotheism are "unitarianism", a belief in one God with one person, and "trinitarianism", a belief in one God with three persons. The term binitarianism is sometimes used self-descriptively.