>>For this reason only can Mary be called the mother of God.<<
If Mary is the "mother of God" and that Son died on the cross and the man/God persona cannot be separated then God the Son died on that cross. Now, we only have two options. Either the "one true God" can be separated or the man/God nature of Jesus can be separated.
We also have another consideration. Jesus said "my God, my God why have you forsaken me". If the man/God nature of Jesus cannot be separated was God forsaking part of God?
Are you getting a sense of how the term "mother of God" can not be used without coming into problems with the rest of scripture?
Like metmom keeps showing. Scripture uses the term "mother of Jesus" and does so for a reason.
Either the “one true God” can be separated or the man/God nature of Jesus can be separated.
Luke 1:28-35 shows that the three persons in one God can act independent of each other. That is the concept of the Trinity; three persons in one God. Mary conceives and bears the Son. The Holy Spirit came upon her and the Most High overshadowed her.
It is also revealed in the baptism of the Lord. Jesus is walking out of the water, the Spirit comes to rest over Him in the form of a dove, and the Father speaks from the heavens.
The Son can call out to the Father on the cross. But we know that the Father did not truly forsake the Son.