What is “The Solemnity of Mary, Mother of God” and why is it celebrated on January 1st?

January 1st is a Holy Day of Obligation in which Mary’s role as Jesus’ mother is celebrated. The Church chose January 1st because it is the 8th day, Octave, of Christmas and, according to Levitical Law, Jesus would have been circumcised when he was eight days old. (1) The title “Mother of God” is given to Mary based on the understanding of the nature of Jesus and the Trinity.

Jesus is the part of the Trinity that became flesh. (2) Mary carried Jesus in her womb and gave birth to Him. Jesus is God and Mary is His mother. Therefore, Mary is the Mother of God.

Ultimately, this day emphasizes Mary’s role in God’s plan as the mother of Jesus. “The divine persons (the Trinity) do not share the one divinity among themselves but each of them is God whole and entire.” (4) The Church celebrates this day to honor Jesus’ divinity and His relationship to Mary.

Citations: (1) Leviticus 12:3, (2) John 1:1-14, (3) John 1:14, (4) ccc 253