Today the Church celebrates the Solemnity of the Immaculate Conception, the solemn dogma defined by Blessed Pope Pius IX in 1854. As Our Lady Immaculately Conceived is the patroness of the United States of America, this is a holy day of obligation in the United States.
Through the centuries the Church has become ever more aware that Mary, "full of grace" through God, was redeemed from the moment of her conception. That is what the dogma of the Immaculate Conception confesses, as Blessed Pope Pius IX proclaimed on December 8, 1854: "The most Blessed Virgin Mary was, from the first moment of her conception, by a singular grace and privilege of almighty God and by virtue of the merits of Jesus Christ, Savior of the human race, preserved immune from all stain of original sin."
~ Catechism of the Catholic Church
"In her sinless perfection, Mary is a great sign of hope for the Church and for the world, a sign of the marvels that God’s grace can accomplish in us, his human creatures. In these days of Advent, in company with the holy and immaculate Mother of God, let us prepare to welcome her Son into our lives and into our hearts." Pope Benedict XVI, on the Feast of the Immaculate Conception 2011
Collect: Father, You prepared the Virgin Mary to be the worthy mother of your Son. You let her share beforehand in the salvation Christ would bring by His death, and kept her sinless from the first moment of her conception. Help us by her prayers to live in your presence without sin. We ask this through our Lord Jesus Christ, your Son, who lives and reigns with you and the Holy Spirit, one God, for ever and ever. Amen.