Welll... I am still not sure how to use this to refute my opponent who claims that Christ's humanity has nothing in common with our present humanity. Damascene says that The Word formed a kind of human flesh, not actually taking anything from His human ancestor, the Theotokos, but creating His own flesh from nothing and using Her as merely an "abode." Besides, nothing from the above passage disporoves my opponent's other idea, the one that in Heaven there is no yesterday or today or tomorrow, so it just cannot be that Christ in Heaven was at any "timepoint" NOT the God-Man He is now (because there aren't any "timepoints" up there).
The statement above is not orthodox at all. They fly completely in the face of the Divine Services for the Feast of the Annunciation.from Vespers, Stichera at Psalm 140
Then the bodiless angel replied:
When God so wills, the order of nature is overcome,
and what is beyond mankind comes to pass.
Believe that my sayings are true,
all-holy and immaculate Lady.
And she cried aloud:
Let it be to me according to your word,and I shall bear Him Who is without flesh, Who shall borrow flesh from me,
that through this mingling He may lead mankind up to its ancient glory,//
for He alone has power so to do!
Gabriel the archangel was sent from heaven
to announce to the Virgin the glad tidings of her conceiving;
coming to Nazareth he pondered in amazement at this wonder:
How shall He Who dwells in the heights,
Whom none can comprehend, be born of a Virgin?
How shall He whose throne is heaven, and whose footstool is the earth,
be held in the womb of a woman?
He upon whom the six-winged seraphim and the many-eyed cherubim cannot gazehas been pleased at a single word to be made flesh of this His creature!
It is the Word of God Who dwells in her.
Why then, do I stand here, and not say to the Maiden:
Rejoice, full of grace, the Lord is with you!
Rejoice, pure Virgin!
Rejoice, unwedded Bride!
Rejoice, Mother of life!//
Blessed is the fruit of your womb!from Vespers Aposticha:
The Theotokos heard the mysterious voice
as the archangel announced the words of glad tidings.
When she accepted this salutation
she conceived You, the eternal God, in her womb.
Therefore we cry out with joy: Unchanging God Who took flesh from her:
Grant peace to the world and to our souls, great mercy! from Matins, the Canon of the Annunciation, Ode 8
Holy Virgin, replied the Angel,
You tell me of the usual manner in which men are born.
But I tell you of the birth of the true God!
In ways that He alone knows, beyond words and understanding, He shall take flesh of you.
Therefore, I cry rejoicing:
All works of the Lord, bless the Lord!
It also makes one question the idea of calling Joachim and Anna the "ancestors of God" as they are repeatedly called in the Divine Services. How can one call the parents of the Theotokos such unless Christ took flesh from their daughter?
Your opponents would do well to read all the services of the Annunciation, I think.