How so? Christ existed as God long before the world or Mary were created. There is no way she could be mother of his divine side. She is as human and you and I are, she was not sinless and needed a savior the same as you and I.I am speaking carefully, slowly, in small words. Most of all I am speaking truth.
Point being, my understanding is that when they were talking about Mary as "Theotokos" (mother of God) they weren't so much talking about Mary, as asserting something about Christ, the incarnation, and the the divine and human natures of Christ.
Do you happen to know when the Spirit enters the soul of the body? ... Neither do I.
Except that renaming Mary as *mother of God* does not even reference Christ anymore. It makes it all about Mary and removes any mention of Jesus.
If they were interested in making it about it Jesus, they'd have kept mention of Him and used the title the HOLY SPIRIT gave her in Scripture.