FOURTH ECUMENICAL COUNCIL

''The "Fourth Ecumenical Council" can refer to two councils'':

★ Oriental Orthodoxy considers this to be the Second Council of Ephesus. The Oriental Orthodox are also known as Miaphysites or "Non-Chalcedonians". This council was held in 449.

★ The Byzantine Orthodox Church, Catholic Church, and some Protestant Churches (ie: Anglican Communion) consider this term to refer to the Council of Chalcedon. They are also known as Dyophysites or "Chalcedonians". This council was held in 451.
Both parties claim to have the true "Orthodox" teaching. This was the beginning of the Schism between the Oriental Orthodox and the rest of mainstream Christianity.