Hypostatic union

Hypostasis denotes an actual, concrete existence, in contrast to abstract categories such as Platonic ideals.

[8] This paradox can only be resolved, Kierkegaard believed, by a leap of faith away from one's understanding and reason towards belief in God.

The Council of Ephesus in 431, under the leadership of Cyril himself as well as the Ephesian bishop Memnon, labeled Nestorius a neo-adoptionist, implying that the man Jesus is divine and the Son of God only by grace and not by nature, and deposed him as a heretic.

In his letter to Nestorius, Cyril used the term "hypostatic" (Greek, καθ᾽ ὑπόστασιν kath' hypóstasin) to refer to Christ's divine and human natures being one, saying, "We must follow these words and teachings, keeping in mind what 'having been made flesh' means .... We say ... that the Word, by having united to himself hypostatically flesh animated by a rational soul, inexplicably and incomprehensibly became man."

Cyril also stressed on "μία φύσις τοῦ θεοῦ λόγου σεσαρκωμένη, meaning "one physis ["nature"] of the Word of God made flesh" (or "one physis of God the Word made flesh")"[10] The preeminent Antiochene theologian Theodore of Mopsuestia, contending against the monophysite heresy of Apollinarism, is believed to have taught that in Christ there are two natures (dyophysite), human and divine, and two corresponding hypostases (in the sense of "subject", "essence" but not "person") which co-existed.

[11] However, in Theodore's time the word hypostasis could be used in a sense synonymous with ousia (which clearly means "essence" rather than "person") as it had been used by Tatian and Origen.

The Greek and Latin interpretations of Theodore's Christology have come under scrutiny since the recovery of his Catechetical Orations in the Syriac language.

However, the Oriental Orthodox persistently 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 be referred to as a reference to Cyrillian Christology, which used the phrase "μία φύσις τοῦ θεοῦ λόγου σεσαρκωμένη", "mía phýsis toû theoû lógou sesarkōménē".