(theology, religion, Christianity, historical) The belief that God is composed of three persons (Father, Son, Holy Spirit) and a divine essence.
1865, William Greenough Thayer Shedd, A History of Christian Doctrine, Volume 1, 3rd Edition, page 377,Roscellin was accused of tritheism, and Gilbert of Poictiers of Damian's old heresy of tetratheism.
1996, Louis Berkhof, Systematic Theology, page 88,From this it follows that the divine essence is not an independent existence alongside of the three persons. It has no existence outside of and apart from the three persons. If it did, there would be no true unity, but a division that would lead into tetratheism.
2004, Herman Bavinck, John Bolt, John Vriend, Reformed Dogmatics: God and Creation, page 293,When in addition the divine being is viewed in a Platonic-realistic sense, tritheism turns into tetratheism, an error with which Damian of Alexandria was charged.
