Christ was/is God. His humanity and his divine nature are forever intertwined. It was Christ, God and man who died on the Cross -- it was not the Father nor the Spirit, but God the Son who died on the Cross. It was not some man possessed by the spirit by God.
if we say Mary bore just the human nature, we are splitting the nature of Christ into two.
Mary bore God, not just a human "possesed by the spirit of God"
Mary was/is God's creation and it is a miracle and a sign of God's ability to humble Himself that He was borne by one of His creations.
See post #183 above.