On May 23, 451, the Eastern emperor, Marcian, summoned an ecumenical council of bishops that he helped would “end disputations and settle the true faith more clearly and for all time.” They met at Chalcedon, just across the Bosporus from Marcian’s imperial capital of Constantinople. About 520 bishops attended, all but four from the eastern half of the Roman Empire. Nicaea had settled the momentous question of the eternal relationship between the Son and the Father, but it raised questions regarding the relationships between the human and divine natures of Jesus Christ. The bishops met for fifteen arduous sessions between October 8 and November 10 and they came up with an answer that answered the question for which it had been called. And that answer has stood the test of time: Jesus was one person consisting of two natures. But before they came up with this time-tested answer, there was plenty of passionate controversy. In general, those theologians who were linked with Alexandria emphasized the deity of Christ; those sided with Antioch emphasized his humanity at the expense of his deity.

One controversial view that did injustice to Christ’s true humanity was developed by Appolinarius (c.310-c.390), rhetoric teacher and bishop of Laodicea. He developed this view when he was around age 60. Before this point, he was a good friend of Athanasius and a notable champion of orthodoxy. In order to avoid the undue separation of the human and divine natures of Christ, Apollinarius taught that Christ had a true body and soul but that his spirit was replaced by the logos. This logos as the divine element actively dominated the passive element, the body and soul, in the person of Christ. He stressed the deity of Christ but minimized his humanity. This view was officially condemned at the Council of Constantinople in 381.

In contrast to this was the view developed by Nestorius (c.381-c.452), a scholarly monk who became patriarch of Constantinople in 428. He disliked the term theotokos (God-bearer) as a name for Mary, the mother of Jesus, because it seemed to exalt her unduly. He offered the term Christotokos, as an alternative, arguing that Mary was only the mother of his human side. By doing this, he made Christ out to be a man, in whom, in Siamese twin fashion, the divine and human natures were combined in a mechanical union rather than in an organic union of natures. Christ was in essence only a perfect man who was morally linked to deity. He was a God-bearer rather than the God-man. The leaders at the Council of Ephesus in 431 condemned this doctrine. Yet the followers of Nestorius continued their work in the eastern half of the empire and carried their version of the gospel to Persia, India and even China in 635.

Enter into the fray, Pope Leo I also known as “the Great” due to his talent, seriousness, and dedication and because of his lasting importance in the history of Christian thought. His driving goal in doctrine as well as church order was to secure stability in an age of fragmentation. Leo’s response to this controversy, known as his Tome, took a straightforward response: Jesus was a single person with two natures. Leo walked a tightrope that many had fallen off of. Each form of Christ as God and man “carries on its proper activities in communication with the other.” With these words, Leo kept together distinctiveness of natures along with unity of person. This later became a cornerstone of the definition at Chalcedon.

After intense debate, the emperor Marcian himself read aloud the definition formulated on October 25, 451:

Following the holy fathers, we confess with one voice that the one and only Son, our Lord Jesus Christ, is perfect in Godhead and perfect in manhood, truly God and truly man, and that he has a rational soul and a body. He is of one substance with the Father as God, he is also of one substance with us as man. He is like us in all things except sin. He has begotten of his Father before the ages as God, but in these last days and for our salvation he was born of Mary the virgin, the theotokos, as man. This one and the same Christ, Son, Lord, Only-Begotten is made known in two natures which exist without confusion, without change, without division, without separation. The distinction of the nature in no way taken away by their union, but rather the distinctive properties of each nature are preserved. Both natures unite into one person and one hypostasis, that is substance. They are not separated or divided into two persons, but they form one and the same Son, Only-begotten, God, Word, Lord Jesus Christ, just as the prophets of old have spoken concerning him and as the Lord Jesus Christ has taught us and as the creeds of the fathers has delivered to us.

Chalcedon had important theological consequences. Of first importance was the way the balanced statement of Chalcedon articulated fundamental Christian doctrine. It reflected the teachings of the New Testament with commendable caution. In a way, it constructed a fence within which further reflection upon the person could continue. Whatever else might be said, it was always necessary to affirm Christ as one person with two natures. Getting questions right about the personhood of Jesus Christ was important because Christ and what he did were of immeasurable significance. Chalcedon preserved room for further thought on the person of Christ while it gave reassurance for the great work of salvation this Son of God  performed.

Second, Chalcedon marked the successful translation of the Christian faith out of its Jewish context (where words and concepts were shaped mainly by the Old Testament) into the Hellenistic (Greek) context (where words and concepts were shaped mainly by Greek thought and Roman might). For the Greek world, what occurred at the Council of Chalcedon could not be more important. Chalcedon showed that the heart of the gospel message could be preserved even in new conceptual language. The terms ousia, hypostatis, substantia, and persona are not found in scripture and the biblical world has very little connection to the conceptual worlds in which these terms arose. “Yet Chalcedon showed that the message of God becoming incarnate to effect the salvation of his people was a message that could be heard distinctly, adequately, and powerfully in precisely these extrascriptural terms and within that non-Judaic intellectual milieu.” (Noll)

Lastly, Chalcedon was not Pentecost. But because it faithfully synthesized scriptural history, the people of the Greek world could now hear the “wonders of God” in their own tongue. Because Chalcedon’s work faithfully translated scriptural teaching, Greeks would now express those wonders of the Lord God in its own conceptual terms. This synthesis and translation would need to happen again and again.

The Definition of Chalcedon retains its momentous importance not just because it is such a skillful and well-balanced statement. It also faithfully represents the reality about which it speaks. We Christians can live in the world and for the glory of God we serve and worship, because the fact of one “person” can coexist with the fact of two “natures” because it really happened, as the apostle John attests, that “the Word became flesh and dwelt among us.” (John 1:14)