ROME – Pope Leo XIV marked the traditional Marian feast of the Immaculate Conception urging faithful to imitate the Virgin Mary in embracing God’s plan for their lives, and to thus collaborate with him in changing the world.

One of a handful of so-called “holy days of obligation” on the Catholic liturgical calendar, in which faithful are required to go to Mass, the solemnity of the Immaculate Conception commemorates the conception of the Virgin Mary without original sin.

In a special festive Angelus address for the Dec. 8 feast, the pope said God granted Mary “the extraordinary grace of a completely pure heart, in view of an even greater miracle: The coming of Christ the Savior into the world as man.”

Recalling the scripture passage recounting the Annunciation, when the Archangel Gabriel greeted Mary as “full of grace” and proclaimed that she would give birth to the Messiah, Mary responded with complete faith, Leo said, saying, “I am the handmaid of the Lord; let it be to me according to your word.”

Quoting Saint Augustin, the founder of his own Augustinian Order, the pope said that in that moment, “Mary believed, and what she believed was fulfilled in her.”

“The gift of the fullness of grace, in the young woman of Nazareth, was able to bear fruit because she in her freedom welcomed it, embracing the plan of God,” he said, saying, “the Lord always acts in this way: he gives us great gifts, but he leaves us free to accept them or not.”

Mary’s belief in God’s word and her trust in his plan of salvation, conveyed with her simple fiat, he said, was not just relevant for her, but was a gift for the whole of humanity.

Leo said that because of this, the feast of the Immaculate Conception is a source of joy, and is an invitation for faithful “to believe as she believed, giving our generous assent to the mission to which the Lord calls us.”

The “miracle” of Mary’s conception without sin was extended to all believers through the sacrament of Baptism, in which the recipients are “cleansed from original sin, we have become children of God, his dwelling place and the temple of his Spirit.”

“Just as Mary, by means of a special grace, was able to welcome Jesus in herself and give him to all people, so too baptism allows Christ to live in us and allows us to live united with him, to cooperate in the Church, each according to his or her condition, for the transformation of the world,” the pope said.

Pope Leo encouraged believers to imitate Mary in repeating their own “yes” to God and his plans daily, “with gratitude, humility and perseverance, in prayer and in concrete acts of love, from the most extraordinary gestures to the most mundane and ordinary efforts and acts of service.”

“In this way, Christ can be known, welcomed and loved everywhere and salvation can come to everyone,” he said.

After leading faithful in praying the traditional Marian prayer of the Angelus, the pope entrusted to Mary “our constant prayer for peace” throughout the world.

Later on Monday afternoon was scheduled to lay a wreath of flowers at the foot of the pillar of the Immaculate Conception in Rome’s Piazza di Spagna, as is tradition for the Marian feast.

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