Mary, the Holy Mother of God

The Solemnity of Mary, Holy Mother of God is a liturgical celebration observed on January 1st which falls exactly one week after Christmas, the end of the octave of Christmas.

The Blessed Virgin Mary is honored as the Mother of God because she conceived and gave birth to Christ, who is the incarnation of God the Son, the Second Person of the Blessed Trinity. It is fitting to honor Mary as Mother of Jesus, following the birth of Christ. When Catholics celebrate the Solemnity of Mary Mother of God, we are not only honoring Mary, who was chosen among all women throughout history to bear God incarnate, but we are also honoring our Lord, who is fully God and fully human.

Since the first centuries of Christianity, the Church customarily has regarded the Blessed Virgin Mary to be the Mother of God for a simple, logical reason;
By the power of the Holy Spirit, she conceived Jesus Christ, the Son of God.
The Church solemnly defined this belief at the Ecumenical Council of Ephesus AD 431.