Still, the opinion is often expressed in Western
theological literature that Byzantine Christology is crypto-Monophysite, and
offered as an explanation for the lack of concern among Eastern Christians
for man in his secular or social creativity.
God and Man
To affirm that God became man, and that
His humanity possesses all the characteristics proper to human nature,
implies that the Incarnation is a cosmic event. Man was created as the
master of the cosmos and called by the creator to draw all creation to God.
His failure to do so was a cosmic catastrophe, which could be repaired only
by the creator Himself. Moreover, the fact of the Incarnation implies that
the bond between God and man, which has been expressed in the Biblical
concept of "image and likeness," is unbreakable. The restoration of creation
is a "new creation," but it does not establish a new pattern, so far as man
is concerned; it reinstates man in his original divine glory among creatures
and in his original responsibility for the world. It reaffirms that man is
truly man when he participates in the life of God; that he is not
autonomous, either in relation to God, or in relation to the world; that
true human life can never be "secular." In Jesus Christ, God and man are
one; in Him, therefore, God becomes accessible not by superseding or
eliminating the humanity, but by realizing and manifesting humanity in its
purest and most authentic form.

Redemption and Deification
The Chalcedonian definition proclaimed that Christ is consubstantial, not
only with His Father, but also "with us." Though fully man, Christ does not
possess a human hypostasis, for the hypostasis of His two natures is the
divine hypostasis of the Logos. Each human individual, fully
"consubstantial" with his fellow men, is, nonetheless, radically distinct
from them in his unique, unrepeatable, and inassimilable personality or
hypostasis: no man can fully be in another man. But Jesus' hypostasis has a
fundamental affinity with all human personalities: that of being their
model. For indeed all men are created according to the image of God, i.e.,
according to the image of the Logos. When the Logos became incarnate, the
divine stamp matched all its imprints: God assumed humanity in a way which
did not exclude any human hypostasis, but which opened to all of them the
possibility of restoring their unity in Himself. He became, indeed, the "new
Adam," in whom every man finds his own nature realized perfectly and fully,
without the limitations which would have been inevitable if Jesus were only
a human personality.

The Theotokos
The only doctrinal definition on Mary to which the Byzantine
Church was formally committed is the decree of the Council of Ephesus which
called her the
Theotokos, or "Mother of God."
Obviously Christological, and
not Mariological, the decree nevertheless corresponds to the Mariological
theme of the "New Eve," which has appeared in Christian theological
literature since the second century and which testifies, in the light of the
Eastern view on the Adamic inheritance, to a concept of human freedom more
optimistic than that which prevailed in the West.
But it is the theology of Cyril of Alexandria,
affirming the personal, hypostatic identity of Jesus with the pre-existent
Logos, as it was endorsed in Ephesus, which served as the Christological
basis for the tremendous development of piety centered on the person of Mary
after the fifth century. God became our Savior by becoming man; but this
"humanization" of God came about through Mary, who is thus inseparable from
the person and work of her Son. Since in Jesus there is no human hypostasis,
and since a mother can be mother only of "someone," not of something, Mary
is indeed the mother of the incarnate Logos, the "Mother of God." And since
the deification of man takes place "in Christ," she is also - in a sense
just as real as man's participation "in Christ" - the mother of the whole
body of the Church.

From: Byzantine Theology by John Meyendorff,
Fordham University Press, New York, NY, 1979