Concept

Council of Chalcedon

Intro

In the year 451, about 500 bishops met in a town called Chalcedon, just across the water from Constantinople, to settle a long-running fight about Jesus.

The Council of Nicaea in 325 had already said Jesus is fully God. The Council of Constantinople in 381 had reaffirmed that. But a new question had arisen. If Jesus is fully God and fully human, how exactly do those two natures fit together in one Person? Did His divine nature absorb His human nature? Did He have two separate consciousnesses? Was there really one Christ, or two?

Two extreme answers had developed and each had drawn followers. Nestorius taught (or was accused of teaching) that Christ was effectively two persons, one divine and one human, sharing one body. Eutyches taught the opposite, that Christ's human nature was swallowed up by His divine nature, leaving only one mixed nature. Both extremes seemed to lose something the gospel needed.

The bishops at Chalcedon settled it with a formula now called the Chalcedonian Definition. Jesus Christ is one Person in two natures, divine and human, "without confusion, without change, without division, without separation." Four words held the line: no mixing of the two natures, no changing them into each other, no dividing the one Person, no separating the natures into two persons.

Chalcedon is the foundational settlement of orthodox Christology for the great Latin (Roman Catholic), Byzantine (Eastern Orthodox), and Reformation (Lutheran, Reformed, Anglican) traditions. It is also the council whose definition the Coptic, Ethiopian, Eritrean, Syriac, and Armenian Orthodox churches rejected; they form the Oriental Orthodox family and have their own (often misunderstood) "miaphysite" position.

This page lays out the controversies that led to the council, the political situation, the text of the definition, and the lasting divisions.

In full

The Council of Chalcedon (451 CE), the Fourth Ecumenical Council, was convened in the city of Chalcedon (across the Bosphorus from Constantinople; modern Kadıköy, Turkey) by the Eastern Roman Emperor Marcian and Empress Pulcheria. It addressed the Christological controversies that had split the church in the decades after Nicaea and Constantinople, producing the Chalcedonian Definition, the formula declaring that Jesus Christ is one Person in two natures, divine and human, "without confusion, without change, without division, without separation." Chalcedon is the foundational settlement of orthodox Christology for the great Latin (Catholic), Byzantine (Eastern Orthodox), and Reformation (Lutheran, Reformed, Anglican) traditions. It is also the council whose definition was rejected by the Coptic, Ethiopian, Eritrean, Syriac Orthodox, and Armenian Apostolic churches, the Oriental Orthodox family, sometimes (controversially) called the "non-Chalcedonian" or "Miaphysite" churches.

The controversies it addressed

By 451 the church had inherited two opposite Christological errors that earlier councils had begun to reject but had not finally settled:

Nestorianism (Nestorius, Patriarch of Constantinople, condemned at the Council of Ephesus, 431). Pressed the distinction of the divine and human natures of Christ so far that Christ appeared to be two persons loosely united, a divine Logos and a human Jesus working in concert. Nestorius famously refused the term Theotokos ("God-bearer") for Mary, preferring Christotokos, implying that Mary bore only the human Jesus, not God the Son.
Eutychianism / Monophysitism (Eutyches, archimandrite at Constantinople, condemned at Chalcedon). The opposite extreme: Christ has one nature after the union, typically read as the human nature being absorbed into the divine, like a drop of vinegar in the ocean. The Eutychian formula: "two natures before the union, one nature after."

The council also had to address the so-called "Robber Council" of Ephesus (449), in which Dioscorus of Alexandria, siding with Eutyches, had bullied through a monophysite verdict and deposed Flavian of Constantinople. Pope Leo I had refused to receive that council and pressed for a new one.

Setting

Convener: Emperor Marcian, with Pulcheria's support; Pope Leo I had pushed for a Western council but consented to Chalcedon.
Location: Chalcedon (Kadıköy), across the strait from Constantinople, close enough for imperial oversight.
Date: October 8, November 1, 451 CE.
Attendance: Approximately 500-630 bishops, the largest ecumenical gathering to that point. Predominantly Eastern; papal legates represented Leo of Rome.
Key documents: Cyril of Alexandria's Letters (especially the Second Letter to Nestorius and the Letter to John of Antioch) accepted as Christological touchstones; Pope Leo's Tome to Flavian (449) read aloud and acclaimed by the bishops with the famous cry: "Peter has spoken through Leo!"

The Chalcedonian Definition

The core text, preceded by reaffirmation of Nicaea (325) and Constantinople (381) and acceptance of Cyril's letters and Leo's Tome:

"Following the holy fathers, we all unanimously teach that our Lord Jesus Christ is to us one and the same Son, the self-same perfect in Godhead, the self-same perfect in manhood; truly God and truly man; the self-same of a rational soul and body; consubstantial (homoousios) with the Father according to the Godhead, the self-same consubstantial with us according to the manhood; like us in all things, sin apart; before the ages begotten of the Father as to the Godhead, but in the last days, the self-same, for us and for our salvation, born of Mary the Virgin Theotokos as to the manhood;

one and the same Christ, Son, Lord, Only-begotten, made known in two natures [en dyo physesin] without confusion, without change, without division, without separation [asynchytōs, atreptōs, adiairetōs, achōristōs];

the difference of the natures being in no way removed because of the union, but rather the property of each nature being preserved and concurring into one Person and one Hypostasis, not parted or divided into two Persons, but one and the same Son and Only-begotten God Word, Lord Jesus Christ."

The four "without"s, the Chalcedonian negatives, are the formula's central genius. They do not explain the union; they fence it against the four major errors:

Negative	Excluded error
Without confusion (asynchytōs)	Eutychianism / Monophysitism (natures blended into one)
Without change (atreptōs)	Either nature transformed into the other
Without division (adiairetōs)	Nestorianism (two persons, two acting subjects)
Without separation (achōristōs)	Two Christs, divine Logos and human Jesus loosely associated

Theological architecture

Chalcedon's grammar:

One Person (hypostasis / prosōpon). A single subject, the eternal Son of God incarnate. Whatever Jesus does, the Son of God does.
Two natures (physeis). Each retains its own properties; the divine remains divine (omniscient, omnipotent, eternal), the human remains human (limited in knowledge, suffering, capable of dying).
The communicatio idiomatum ("communication of attributes"). Because the natures are united in one Person, properties of each may be predicated of the Person, "the Lord of glory was crucified" (1 Cor 2:8); "they crucified the Lord of glory."
Theotokos affirmed. Mary is "God-bearer" because the one she bore is God the Son in the flesh. Refusing Theotokos implies refusing the unity of Christ's Person.

Aftermath: the Oriental Orthodox split

The Chalcedonian formula was not received by significant portions of the Eastern church, especially in Egypt, Syria, Armenia, and Ethiopia. The dissenting churches, typically self-described as Miaphysite (one united nature of the Word incarnate, after Cyril's mia physis tou Theou Logou sesarkōmenē) rather than Eutychian Monophysite (one absorbed nature), felt that the "in two natures" language sundered Christ. They preferred Cyril of Alexandria's pre-Chalcedonian language: "out of two natures, one." The split has lasted to the present and constitutes the Oriental Orthodox family, distinct from both Roman Catholic and Eastern (Chalcedonian) Orthodox communions:

Coptic Orthodox Church (Egypt)
Ethiopian Orthodox Tewahedo Church
Eritrean Orthodox Tewahedo Church
Syriac Orthodox Church
Armenian Apostolic Church
Malankara Orthodox Syrian Church (India)

20th and 21st-century ecumenical dialogue (notably the 1989 and 1990 Joint Statements of the Eastern and Oriental Orthodox, and parallel Roman Catholic, Oriental Orthodox declarations) has reached substantial Christological agreement: both sides affirm one Person, both reject Eutychian absorption, both confess the full deity and full humanity of Christ. The remaining differences are partly terminological (one nature of the Word incarnate vs in two natures), partly historical (the sting of mutual anathemas across 1,500 years).

Spread of positions

Roman Catholic, Eastern Orthodox, Lutheran, Reformed, Anglican, most evangelical confessions. Receive Chalcedon as binding orthodox Christology. Augsburg Confession III; Belgic Confession XVIII-XIX; Westminster Confession VIII; Thirty-Nine Articles II.
Oriental Orthodox (Coptic, Ethiopian, Eritrean, Syriac, Armenian, Malankara). Reject the Chalcedonian formula but in current dialogue affirm essentially Chalcedonian substance.
Assyrian Church of the East. Sometimes labeled Nestorian, but its current Christology affirms one Christ in two natures and two qnōmē (a term that does not map cleanly to hypostasis); ecumenical dialogue has reduced the historic distance.
Modern liberal Christology (Schleiermacher, Ritschl, the 19th-century kenoticists, some post-Bultmannians). Often argues Chalcedon is metaphysically obsolete; replaces "two natures" with degree-Christology, function-Christology, or symbol. Mainstream confessional response: such proposals abandon the Christ of the New Testament.
Mormons / JWs / Oneness Pentecostals. Reject Chalcedon outright (each for different reasons rooted in their non-Nicene starting points).

Tensions

Two-nature vs one-nature language. The substantial Christological agreement of recent dialogue does not fully erase the historical wound or the philosophical preference for one or the other formula. Reformed and Catholic theologians both note the Miaphysite intent often was orthodox; the Coptic and Armenian intent today is plainly orthodox.
The communicatio idiomatum. Lutherans extended it (the genus maiestaticum: divine attributes really shared with the human nature, used to underwrite the bodily ubiquity of Christ in the Lord's Supper) further than Reformed (Calvin, with the extra Calvinisticum: even in the incarnation, the divine Logos remained also "outside" the body of Jesus, sustaining the universe). Christological wing of the Lutheran-Reformed Eucharistic dispute.
Constantinople II (553) clarified Chalcedon by affirming the enhypostatic union, the human nature has its personal subsistence in the Person of the Logos, not as an independent person. Constantinople III (681) extended the same logic to the will: two wills, divine and human, one Person.
Implications for atonement. That Christ is fully human is what allows him to bear the human curse (Heb 2:14-17); that he is fully God is what gives the bearing infinite worth (cf. Penal Substitutionary Atonement). Chalcedon's structure is load-bearing for the gospel.