Chalcedonian Christology (Two Natures in One Person)

In 451 the Council of Chalcedon met to settle a dispute that had already split the church over how to describe Jesus Christ's divine and human natures. The council's definition, since known as the Chalcedonian formula, declared that Christ is fully God and fully man, one person known in two natures that exist without confusion, without change, without division and without separation. Each nature keeps its own properties intact; divinity is not diluted by humanity, and humanity is not swallowed up into divinity, yet the two are not two separate persons loosely joined but a single subject, the eternal Son, who possesses both natures completely. The formula was built to reject two opposite errors the council judged had already led churches astray. Nestorius had been read as dividing Christ into two persons, one divine and one human, joined only loosely, so that Mary could be called mother of the human Jesus but not mother of God. Eutyches, on the other side, was judged to have taught that Christ's humanity was absorbed into his divinity after the union, leaving only one composite nature. Chalcedon's four negative adverbs, without confusion, without change, without division, without separation, were chosen precisely to rule out both errors at once, holding that the union is real and complete while the distinction between the two natures is never erased.

Chalcedon's definition became the standard confession of Christ's person for the churches that trace their line through Rome, Constantinople and the later Protestant churches, all of which count Chalcedon among the councils that carry binding doctrinal weight. It did not, however, settle the dispute for everyone at the table. A significant body of churches, centered in Egypt, Syria, Armenia and Ethiopia, judged Chalcedon's language of two natures too close to the very division into two subjects the council claimed to be rejecting, and preferred instead the formula associated with Cyril of Alexandria, one incarnate nature of God the Word, a position now generally called miaphysite rather than the older and less accurate label monophysite. These churches, now known collectively as Oriental Orthodoxy, broke communion with Chalcedon's supporters in the years following 451, a division that has lasted more than fifteen centuries and has only recently been the subject of serious reconciling dialogue. Modern theological conversation between Chalcedonian and Oriental Orthodox churches has increasingly concluded that both sides were affirming the same underlying reality, a real union of full divinity and full humanity in one Christ, disagreeing chiefly over which technical vocabulary best protected that truth against being misread, though the historic ecclesial separation between the two communions remains unresolved to this day.