Council of Chalcedon

The Council of Chalcedon, held from 8 October to 1 November 451 at Chalcedon, across the Bosporus from Constantinople in what is now Istanbul's Kadıköy district, is counted as the fourth of the Church's ecumenical councils. Summoned by the Roman emperor Marcian and attended by some 520 bishops or their representatives, it defined Christ as one person in two natures, divine and human. Its definition became standard teaching for the Catholic and Eastern Orthodox churches but also caused a lasting split with the churches now known as Oriental Orthodox.

The First Council of Nicaea in 325 had declared Christ fully God, of one substance with the Father, and later councils at Constantinople in 381 and Ephesus in 431 confirmed this. The next dispute concerned how divinity and humanity were joined in him. Around 446 Eutyches, an elderly monk in Constantinople, began teaching that after the incarnation Christ's two natures had merged into one. Many understood this as a denial of Christ's full humanity.

In November 448 a synod under Flavian, Bishop of Constantinople, condemned Eutyches. Flavian reported to Pope Leo I, who replied with a doctrinal letter, later known as the Tome of Leo, affirming that Christ had two natures. Eutyches appealed, and Dioscorus, Patriarch of Alexandria, took up his cause.

In 449 Emperor Theodosius II called a council at Ephesus with Dioscorus presiding. It restored Eutyches, refused to read Leo's letter and deposed Flavian and other bishops. According to Chalcedonian accounts Flavian was assaulted and died days later, though other sources dispute who was responsible, or whether the attack happened as described. Leo denounced the meeting as a "synod of robbers", the Latrocinium, and rejected its decisions.

After Theodosius died, the new emperor, Marcian, agreed to a fresh council. Leo wanted it held in Italy, but Marcian chose Chalcedon, close to the capital. Sessions took place in the church of St Euphemia, with papal legates as formal presidents and imperial officials directing business. Dioscorus was tried, and when he refused to appear he was condemned and exiled, though Oriental Orthodox tradition holds that he was kept under arrest.

The bishops at first resisted writing a new creed. Letters of Cyril of Alexandria and Leo's Tome were read and acclaimed, and a committee found that the Tome agreed with Cyril's teaching. But thirteen Egyptian bishops refused to sign, and under pressure from the emperor a new statement of faith was drafted.

The definition confessed one and the same Christ, complete in both godhead and manhood, existing in two natures that are neither mixed, changed, divided nor separated, and united in one person. It also confirmed the creeds of Nicaea and Constantinople. The council issued disciplinary canons and gave the Bishop of Jerusalem independent authority over the three Palestinian provinces. A further canon, known as canon 28, gave the see of Constantinople, as the "New Rome", privileges equal to those of Rome and second rank after it. Leo rejected that canon while approving the council's teaching on faith, but the Eastern Orthodox Church continues to regard it as valid.

Many bishops in Egypt and Syria saw the language of two natures as a revival of Nestorianism and rejected the council. A schism followed in which the churches of Alexandria and Antioch split between supporters and opponents of Chalcedon. Imperial efforts to enforce the council brought persecution of its opponents in Egypt, where the Copts came to call it "Chalcedon, the Ominous", and Justinian I later pressed dissenting monks to accept it or lose their posts. Some historians argue that these divisions weakened the eastern provinces of the Byzantine Empire before the Persian and Arab invasions.

The Catholic and Eastern Orthodox churches, and most Protestant churches, accept Chalcedon's teaching. The Oriental Orthodox churches, including the Coptic and Syriac Orthodox churches, reject it, describing their own position as miaphysite rather than monophysite. In recent decades a degree of rapprochement has developed between the two traditions.

Our 400 and 500 maps show the Eastern Roman Empire, whose emperor called the council, with Chalcedon on the Asian shore facing Constantinople in present-day Turkey.