Second Council of Ephesus

The Second Council of Ephesus was a Christological church synod in 449 AD convened by Emperor Theodosius II under the presidency of Pope Dioscorus I of Alexandria. It was intended to be an ecumenical council, and it is accepted as such by the miaphysite churches but was rejected by the Chalcedonian dyophysites. It was explicitly repudiated by the next council, the Council of Chalcedon of 451, recognised as the fourth ecumenical council by Chalcedonian Christians, and it was named the Latrocinium or "Robber Council" by Pope Leo I. The Chalcedonian churches, particularly the Roman Catholic and Eastern Orthodox communions, continue to accept this designation, while the Oriental Orthodox repudiate it.

Both this council and that at Chalcedon dealt primarily with Christology, the study of the nature of Christ. Both councils affirmed the doctrine of the hypostatic union and upheld the orthodox Christian doctrine that Jesus Christ is both fully God and fully man. The Second Council of Ephesus decreed the formula of Cyril of Alexandria, stating that Christ is one incarnate nature [mia physis] , fully human and fully God, united without separation, without confusion, without mixture and without alteration. The Council of Chalcedon decreed that in Christ two natures exist, "a divine nature [physis] and a human nature [physis], united in one person [hypostasis], with neither division nor confusion".

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