Mother of God - Blessed Virgin Mary 

The Blessed Virgin Mary is the mother of Jesus. Jesus is the Son of God, for this simple reason, Mary is the mother of the Son of God. 

Jesus is not only the Son of God but is also God, if we contemplate the mystery of the Holy Trinity, by which we say that God is three different persons but one true God.

Jesus is the Word of God incarnate, God Himself. He who said to the Apostle Philip, He who sees me has seen my Father, because the Father and I are One. 

Gospel of Saint John
14:8 Philip said to Jesus: Lord, show us the Father, and it is enough for us.
9 Jesus said to him: I have been for such a long a time with you; and you have not known me? Philip, he that sees me sees the Father also. How can you say, Show us the Father?
10 Do you not believe, that I am in the Father, and the Father in me? The words that I speak to you, I speak not of myself. But the Father who abides in me, is the one who does the works.

John 10:30 I and the Father are one.
According to this affirmation, Jesus is claiming the divinity of the Father and is calling himself equal to God. In other words, Jesus is God. 

Elizabeth praised God and exalted Mary calling her Mother of her Lord, Mother of God.

Luke 1:43 y 43 And why has this happened to me, that the Mother of my Lord should come to me?
Eliz

The Apostol also called Him God: John 20:28 Thomas answered Him: My Lord and my God.  

The Blessed Virgin Mary is the Mother of Jesus, Jesus is God, the Virgin Mary is the Mother of God.

January 1st is the first day of the year. The Holy Catholic Church has dedicated this day as as " Solemnity of Mary, Mother of God " in honor of the blessed maternity of Our Lady.  

Mother of God - Apologetics