Today’s Marian feast is relatively new to the Latin Church. Those familiar will recognize that it was St Paul VI who established the title for Mary as “Mother of the Church” but it was Popr Francis who established the liturgical memorial to be celebrated on the Monday following Pentecost. Hence, it is a moveable memorial.
Theologically the Magisterium indicates that the title of Mother of the Church recognizes the fact that the Holy Theotokos, Mary, Mother of God, was praying in the Cenacle with the Apostles at the Pentecost.
Biblically, it is revealed that Mary is the Mother of God, the mother of Jesus who was with Her Son as many key moments of of the Savior’s ministry and at the Cross when Jesus gave His instructions to Her and the Apostle John, establishing a relationship within the Kingdom of God. Jesus said to Mary, “Woman, behold thy son,” and to St. John (who mystically represents all His disciples), “Behold thy mother.”
The Collect
Lord our God, through your power and goodness the Blessed Virgin, the fairest fruit of your redeeming love, shines forth as the perfect image of the Church; grant to your people on their pilgrim way on earth that, with eyes fixed on Mary, they may follow closely in the footsteps of her Son until they come to that fullness of glory, which now they contemplate in his Mother with hearts filled with joy. Through our Lord Jesus Christ, your Son, who lives and reigns with you in the unity of the Holy Spirit, God, for ever and ever. Amen.