Council of Chalcedon

The event

Building on the unresolved Christological questions left by the Council of Ephesus, further controversy arose over the teaching of Eutyches, an archimandrite in Constantinople who taught that Christ's human nature was effectively absorbed into or overwhelmed by his divine nature after the incarnation, a position later called Miaphysitism or, more polemically by opponents, Monophysitism ("one nature").

A council at Ephesus in 449, later dubbed by opponents the "Robber Council" for its heavy-handed and coercive proceedings, had initially vindicated Eutyches, prompting Pope Leo I to protest strongly and press for a properly convened council to overturn the decision.

Emperor Marcian convened the Council of Chalcedon in 451 with over 500 bishops in attendance, the largest and best-documented of the early ecumenical councils. The council condemned Eutyches, affirmed Leo's own Christological letter (the "Tome of Leo"), and articulated the Chalcedonian Definition: that Christ is one person (hypostasis) existing in two natures (physis), divine and human, "without confusion, without change, without division, without separation."

The council's formula became normative for the Catholic Church, the Eastern Orthodox Church, and most Protestant traditions that followed. However, significant portions of the Eastern church — particularly in Egypt (the Coptic Church), Ethiopia, Armenia, and Syria — rejected the Chalcedonian formula as insufficiently affirming the unity of Christ's nature, forming the Oriental Orthodox communion that remains institutionally and theologically distinct from Chalcedonian Christianity to the present day, a division that has persisted for over a millennium and a half.

Other witnesses

• Acts of the Council of Chalcedon (451)
• Pope Leo I, Tome of Leo

Further reading

• Catholic Encyclopedia (1913): Council of Chalcedon
• Wikisource: The Definition of Faith of Chalcedon — primary source, 1900 translation
• Catholic Encyclopedia (1913): Monophysites and Monophysitism