On January 1, the Catholic Church celebrates the Solemnity of Mary, Mother of God (Theotokos, “God bearer”, in Greek). This proclamation derives solely from the belief that Jesus Christ is God incarnate (John 1:14, 8:58). It affirms a foundational belief about the doctrine of the Trinity. This follows from simple logic:
- Mary is the mother of Jesus Christ
- Jesus is God, the 2nd person of the Trinity, of the same substance as God the Father and the Holy Spirit.
- Thus Mary is the Mother of God
Many protestants disagree with this title Mother of God and state that Mary was only the mother of the human nature of Christ. To answer that, however, a mother doesn’t conceive and give birth to a nature; a mother gives birth to a PERSON. And the person that Mary, conceived bore and gave birth to is the divine person of God, who took on human form. This naturally follows, since Jesus was truly God from the first moment of His conception. The following passage affirms this:
[Luke 1:31,35] And behold, you will conceive in your womb and bear a son, and you shall call his name Jesus.  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 called holy, the Son of God.
Mary is even called “the mother of my Lord” (Luke 1:43) in Scripture itself. The “Lord” is synonymous with God, thus further providing validation for the title “Mother of God”.
As mentioned above, this title is meant to reflect a Christological truth. This ancient title of “Theotokos” was affirmed by the Council of Ephesus in 431 A.D. in order to combat the heresy known as Nestorianism, which claimed that Christ was united as two distinct persons, human and divine. This differs from the true Christology as affirmed by the Christian tradition that Jesus is ONE person, God, in the form of man.
Holy Mary, Mother of God, pray for us!