Christ's humanity was not a mere fleshly shell that God rented and used for a temporary amount of time. God did not just come to live in flesh as a man, but the 'Word became flesh' (John 1:14). God incorporated human nature into His eternal being. In the incarnation humanity has been permanently incorporated into the Godhead. God is now a man in addition to being God. At the virgin conception God acquired an identity He would retain for the rest of eternity.

His human existence is both authentic and permanent. Jesus' humanity is not something that can be discarded or dissolved back into the Godhead, but He will always and forever exist in heaven as a glorified man, albeit God at the same time. Upon his ascension, Jesus was not deified, but rather was glorified.

Contrasting views

A variety of events led up to Chalcedon, but there were three opposing views that deserved the church's attention. Apollinarianism, Nestorianism, and Eutychianism all challenged the view that the one person of Christ included a human and divine nature. While their goals may have been to unify the person or natures, each view was condemned as heresy.

Apollinarianism

Apollinarians argued that in the Incarnation the Son of God assumed a human nature but not a human soul. Instead, his divine nature took the place of the soul. This view diminished the full humanity of Jesus and was condemned at the Council of Constantinople in 381. This view is similar to docetism.

Nestorianism

Nestorianism insisted that there were two natures but that there were also two persons: one divine and the other human. Rather than unifying Jesus, this view separated the person of Jesus along with his two natures.

Eutychianism

This view essentially absorbed the human nature into the divine nature. In an attempt to unify the person of Jesus, Eutychianism denied the two natures of Jesus and affirmed a new, or third, nature. This issue is also similar to that of monophysitism (mono - one; physis - nature).

Monophysitism, Miaphysitism, and Dyophysitism

Adherents of miaphysitism argue that it is different than monophyistism, "mia standing for a composite unity unlike mone standing for an elemental unity" They argue:

"After the Union, Christ was no longer in two natures. The two natures became united into one nature without separation, without confusion and without change. Thus He was at the same tithe perfect God and perfect man.

This is the union of the natures in the Incarnation. After the union Christ is not two persons or two natures, but one Person, one incarnate Nature of God the Son, with one will, but being at once divine and human. The Council of Chalcedon resolutely affirmed dyophysitism over monophysitism and miaphysitism, saying that Christ had two inseparable natures in one person.