Miaphysitism is the Christological doctrine that holds Jesus, the "Incarnate Word, is fully divine and fully human, in one 'nature' (physis)." It is a position held by the Oriental Orthodox Churches and differs from the Chalcedonian position that Jesus is one "person" () in two "natures" (), a divine nature and a human nature (Dyophysitism).
While historically a major point of controversy within Christianity, several modern declarations by both Chalcedonian and Miaphysite churches state that the difference between the two Christological formulations does not reflect any significant difference in belief about the nature of Christ.
Terminology
The word miaphysite derives from the Ancient Greek μία (mía, "one") plus φύσις (phúsis, "nature, substance"). Miaphysite teaching is based on Cyril of Alexandria's formula μία φύσις τοῦ θεοῦ λόγου σεσαρκωμένη, meaning "one physis of the Word of God made flesh" (or "... of God the Word made flesh").
The 451 Council of Chalcedon used physis to mean "nature" (as in "divine nature" and "human nature"), and defined that there was in Jesus one hypostasis (person) but two physeis (natures). It is disputed whether Cyril used physis in that sense. John Anthony McGuckin says that in Cyril's formula "physis serves as a rough semantic equivalent to hypostasis".
Others interpret the Miaphysite term physis in line with its use by the Council of Chalcedon and speak of "Miaphysitism" as "Monophysitism", a word used of all forms of denial of the Chalcedonian doctrine. However, they add that "Miaphysitism" is "the more accurate term for the position held by the Syriac, Coptic and Armenian churches".
The Second Council of Constantinople (553), the ecumenical council that followed that of Chalcedon, accepted Cyril's phrase, but warned against misinterpreting it.
The broad term "Dyophysitism" covers not only the Chalcedonian teaching but also what Nestorianism interpreted as meaning that Jesus is not only of two natures but is in fact two centres of attribution, and thus two persons, a view condemned by the Council of Chalcedon. Similarly, "Monophysitism" covers not only Oriental Orthodox teaching but also the view called Eutychianism, according to which, after the union of the divine and human natures in the incarnation of the eternal Son or Word of God, he has only a single "nature", a synthesis of divine and human, identical with neither. This doctrine is rejected by Miaphysites, who teach instead that the incarnate Christ has one "nature" that is both divine and human in its character, retaining all the characteristics of both humans and divinity, but with no mingling, confusion (pouring together) or change within.
To avoid being confused with Eutychians, the Oriental Orthodox Churches reject the label "Monophysite". Coptic Metropolitan Bishop of Damiette declared it a misnomer to call them Monophysites, for "they always confessed the continuity of existence of the two natures in the one incarnate nature of the Word of God. Non[e] of the natures ceased to exist because of the union and the term 'Mia Physis' denoting the incarnate nature is completely different from the term 'Monophysites'. [...] The Oriental Orthodox do not believe in a single nature in Jesus Christ but rather a united divine-human nature."
The Agreed Statement by the Anglican–Oriental Orthodox International Commission in 2014 said:
Conflict
The conflict over terminology was to some extent a conflict between two renowned theological schools. The Catechetical School of Alexandria focused on the divinity of Christ as the Logos or Word of God and thereby risked leaving his real humanity out of proper consideration (cf. Apollinarism). The stress by the School of Antioch was on the humanity of Jesus as a historical figure. To the theological rivalry between the two schools added a certain political competitiveness between, on the one hand, Alexandria and, on the other, Antioch and Constantinople.