Historic Christian teaching is that the Incarnation means anhypostasia and enhypostasia. Anhypostasia refers to the fact that the Logos did not enter into an already-existing human person; as though there is a discrete "person" apart from the Divine Logos; instead the the Person is the Logos, who is at once both God and man: God because He is eternally God from the Father and man because He is the true offspring of Mary. Enhypostasia refers to the fact that there is not a general humanity through which the Logos is found but the specific person of Jesus. All of this means is that the Logos is Jesus/Jesus is the Logos.
The cluster of cells in Mary's body which divided and divided again is the Very Same through which all things were made, as it is written, "by Him and for Him were all things made".
The Logos did not enter into a child, the Logos is that Child.
And Scripture teaches us this, for what do we read?
"In the sixth month the angel Gabriel was sent by God to a town in Galilee called Nazareth, to a virgin engaged to a man whose name was Joseph, of the house of David. The virgin's name was Mary. And he came to her and said, 'Greetings, favored one! The Lord is with you!' But she was much perplexed by his words and pondered what sort of greeting this might be. The angel said to her, 'Do not be afraid, Mary, for you have found favor with God. And now, you will conceive in your womb and bear a Son, and you will name Him Jesus. He will be great, and will be called the Son of the Most High, and the Lord God will give to Him the throne of His ancestor David. He will reign over the house of Jacob forever, and of His kingdom there will be no end.' Mary said to the angel, 'How can this be, since I am a virgin?' The angel said to her, 'The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the Child to be born will be holy; He will be called the Son of God.'" - Luke 1:26-35
And also,
"In those days, Mary set out and went with haste to a Judean town in the hill country, where she entered the house of Zechariah and greeted Elizabeth. When Elizabeth heard Mary's greeting, the child leaped in her womb. And Elizabeth was filled with the Holy Spirit and exclaimed with a loud cry, 'Blessed are you among women! And blessed is the fruit of your womb. And why has this happened to me, that the mother of my Lord comes to me? For as soon as I heard the sound of your greeting, the child in my womb leaped for joy. And blessed is she who believed that there would be a fulfillment of what was spoken to her by the Lord.'" - Luke 1:39-45
Why would the pre-natal John the Baptist leap for joy unless that which was in Mary's womb is indeed what St. Elizabeth says here, that the Lord Himself--He who is very and truly God, was conceived and there in the womb of Mary, for which reason she is indeed truly called Theotokos, God-bearer.
-CryptoLutheran