Christian theology

=====Hypostatic union=====
{{Main|Hypostatic union|Chalcedonian}}
[[File:Vladimirskaya.jpg|thumb|upright|A depiction of Jesus and Mary, the [[Theotokos of Vladimir]] (12th century)]]
In short, this doctrine states that two natures, one human and one divine, are united in the one person of Christ. The Council further taught that each of these natures, the human and the divine, was distinct and complete. This view is sometimes called [[Dyophysite]] (meaning two natures) by those who rejected it.

Hypostatic union (from the Greek for substance) is a technical term in Christian theology employed in mainstream [[Christology]] to describe the union of two natures, humanity and divinity, in Jesus Christ. A brief definition of the doctrine of two natures can be given as: "Jesus Christ, who is identical with the Son, is one person and one hypostasis in two natures: a human and a divine."<ref>Martin Lembke, lecture in the course "Meetings with the World's Religions", Centre for Theology and Religious Studies, Lund University, Spring Term 2010.</ref>

The [[First Council of Ephesus]] recognised this doctrine and affirmed its importance, stating that the humanity and divinity of Christ are made one according to nature and hypostasis in the [[Logos]].

The [[First Council of Nicaea]] declared that the Father and the Son are of the same substance and are co-eternal. This belief was expressed in the Nicene Creed.

[[Apollinaris of Laodicea]] was the first to use the term hypostasis in trying to understand the [[Incarnation]].<ref>Gregory of Nyssa, ''Antirrheticus adversus Apollinarem''.</ref> Apollinaris described the union of the divine and human in Christ as being of a single nature and having a single essence– a single hypostasis.

The Nestorian [[Theodore of Mopsuestia]] went in the other direction, arguing that in Christ there were two natures ([[dyophysite]]) (human and divine) and two hypostases (in the sense of "essence" or "person") that co-existed.<ref>"Theodore" in ''The Westminster Dictionary of Christian History'', ed. J. Brauer. Philadelphia: Westminster Press, 1971.</ref>

The [[Chalcedonian Creed]] agreed with Theodore that there were two natures in the [[Incarnation]]. However, the [[Council of Chalcedon]] also insisted that hypostasis be used as it was in the Trinitarian definition: to indicate the person and not the nature as with Apollinarius.

Thus, the Council declared that in Christ there are two natures; each retaining its own properties, and together united in one subsistence and in one single person.<ref>[[Enchiridion symbolorum, definitionum et declarationum de rebus fidei et morum|Denzinger]], ed. Bannwart, 148</ref>

As the precise nature of this union is held to defy finite human comprehension, the hypostatic union is also referred to by the alternative term "mystical union."

The [[Oriental Orthodox Church]]es, having rejected the Chalcedonian Creed, were known as [[Monophysites]] because they would only accept a definition that characterized the incarnate Son as having one nature. The [[Chalcedonian]] "in two natures" formula was seen as derived from and akin to a [[Nestorian doctrine|Nestorian]] Christology.<ref>{{cite web|url=http://www.britishorthodox.org/113e.php |title=The Oriental Orthodox Rejection of Chalcedon |access-date=5 October 2006 |url-status=dead |archive-url=https://web.archive.org/web/20080619122112/http://www.britishorthodox.org/113e.php |archive-date=19 June 2008 }}</ref> Contrariwise, the Chalcedonians saw the Oriental Orthodox as tending towards [[Eutychianism|Eutychian]] Monophysitism. However, the Oriental Orthodox have in modern ecumenical dialogue specified that they have never believed in the doctrines of Eutyches, that they have always affirmed that Christ's humanity is consubstantial with our own, and they thus prefer the term "Miaphysite" to refer to themselves (a reference to Cyrillian Christology, which used the phrase "mia physis tou theou logou sesarkomene").

In recent times, leaders from the [[Eastern Orthodox]] and [[Oriental Orthodox]] Churches have signed joint statements in an attempt to work towards reunification.