Mary, Mother of God

Celebrated on January 1, the octave day of Christmas, this is the oldest Marian feast in the Roman Rite. It honors the title Theotokos — God-bearer — defined at Ephesus in 431 against those who would separate Christ's humanity from his divinity. Where Mary is true Mother, the Child is true God. Paul VI also chose this day as the World Day of Peace.

The definition at Ephesus was not primarily a statement about Mary but about Christ: to call her Theotokos is to confess that the one born of her is fully divine and fully human in one person. The feast thus stands as a Christological cornerstone, placed at the threshold of the civil year to remind the faithful that all time belongs to the Lord she bore.