That’s because, as this sub-par Christian can testify, most Christians do not nor can they ever admit to fully understanding the makeup of Almighty God. I question ANY person who says they do.
I agree that no one can fully understand the makeup of Almighty God. But Scripture reveals enough for us to understand that Jesus is God, whole and entire, and because of this, Mary as the mother of Jesus is the mother of God, whole and entire.
I realize that we can go round and round on this ad infinitum, so this will be my last word on it.
I believe that Mary as the mother of Jesus is the mother of God.