What is the Feast of the Immaculate Conception and why is it important to Catholics?

This week on Dec. 8, the Roman Catholic Church celebrated the Solemnity of the Immaculate Conception, one of the most important feast days of the liturgical year. It is also probably the most misunderstood.

The doctrine of the Immaculate Conception teaches that Mary, the Mother of Jesus, was conceived without original sin and her conception was therefore immaculate. It does not refer to the conception of Jesus in his mother’s womb, which is correctly called the Incarnation.

Mary identified herself as the Immaculate Conception to St. Bernadette Soubirous, St. Brigid of Sweden, and St. Catherine Laboure. More than 25 countries, including the United States, are under the patronage of the Immaculate Conception, as is the Diocese of Brooklyn.

Debated by theologians for centuries beginning before the Middle Ages, the nature or status of this identification for Mary wasn’t settled until 1854 when Pope Leo IX formally established the Immaculate Conception as dogma (a belief held with unquestionable certainty), giving it the highest level of authority by making it an infallible teaching.

Says Pope Francis, “The feast of the Immaculate Conception can be summarized by the angel Gabriel’s greeting to Mary as ‘full of grace.’ By calling her ‘full of grace,’ the angel meant that she ‘was full of the presence of God,’ leaving no room in her life for sin. She was created immaculate so that she could welcome fully, with her ‘yes,’ God who was coming into the world”. 

From a Tablet article Dec 11, 2021 by Rita E. Piro.  

Also see:

Fr. Mike Schmitz, YouTube  https://youtu.be/atbpPi0MgcA

Fr. Steve Grunow, Word on Fire Blog https://www.wordonfire.org/resources/blog/what-the-immaculate-conception-means/34971/