And whence is this to me, that the mother of my Lord should come to me? For, lo, as soon as the voice of thy salutation sounded in mine ears, the babe leaped in my womb for joy. - Luke 1:43-44

There is a common misunderstanding about Mary’s relationship to the Son of God. This text clears it up easily. Mary is not the mother of God. Mary is the mother of the Lord. 

As we have studied in previous posts, the Son of God has always existed. He is called by various names, including The Word, but Scripture is very clear that the relationship of the Son and the Father in the Godhead is an eternal one.  Therefore, Mary cannot be the mother of God.

Mary’s humility throughout this entire chapter should warn against any idea of worshipping Mary in any way. She calls herself the handmaid of God, not the mother of God. Mary was blessed beyond any woman in history, but it was not because she had any special merit of her own.  She was blessed to that great extent because of the mercy of God.

Elisabeth, speaking prophetically, is confirming to Mary that the babe in her womb is the Messiah.  Her testimony is the same as John’s gospel, “the Word was made flesh and dwelt among us.” Mary is the mother of the fleshly nature of Jesus. She is the mother of the body that was united to the Eternal Son. It is in this way that she is mother of the Lord because Jesus had to come in the flesh to redeem those in the flesh.