The Confession from the Council of Chalcedon
sometimes called the Chalcedonian Creed

The Council of Chalcedon was held in Chalcedon, near Constantinople in 451. Then as now Christological issues plagued the church. Though this confession is strictly speaking not a creed the declaration did split the Church. There are non-Chalcedonian churches extant today known collectively as oriental orthodoxy. Within this tradition are a number of ancient Christian churches including the Coptic Orthodox Church of Alexandria, the Syriac Orthodox Church (sometimes referred to as "Jacobite"), the Armenian Apostolic Church, the Ethiopian Orthodox Tewahedo Church, the Eritrean Orthodox Tewahedo Church and the Malankara Orthodox Syrian Church. (Tewahedo is from Geez, an Ethiopian language, and means unified. Malankara is a region in what is presently India.)

Following the holy Fathers, we unanimously teach and confess one and the same Son, our Lord Jesus Christ: the same perfect in divinity and perfect in humanity, the same truly God and truly man, composed of rational soul and body; consubstantial with the Father as to his divinity and consubstantial with us as to his humanity; "like us in all things but sin." He was begotten from the Father before all ages as to his divinity and in these last days, for us and for our salvation, was born as to his humanity of the virgin Mary, the Mother of God.

We confess that one and the same Christ, Lord, and only-begotten Son, is to be acknowledged in two natures without confusion, change, division, or separation. The distinction between natures was never abolished by their union, but rather the character proper to each of the two natures was preserved as they came together in one person (prosopon) and one hypostasis*. (Wikipedia 10/18/07)

*Hypostasis is now a technical term meaning:
a. Any of the persons of the Trinity.
b. The essential person of Jesus in which his human and divine natures are united.

More generally hypostasis (Greek: ὑπόστασις) is the underlying state or underlying substance and is the fundamental reality that supports all else. In classical time it was used in a strictly material sense.