There seems to be a widespread misunderstanding of the word “Immaculate Conception.” Most of us think it is the conception of Jesus by Mary, who is a virgin. Because of this, the “Immaculate Conception” is sometimes jokingly referred to as the “Immaculate Misconception”.
The conception of Jesus by Mary is called the Incarnation of Christ. To incarnate means to become flesh. The Son of God, became flesh; He became man. The conception of Mary by Anne, on the other hand, is called Immaculate Conception. Immaculate means without stain. Mary was free from original sin at the moment of her conception.
We celebrate the Incarnation of Christ (also called the Annunciation) on March 25, nine months before Christmas Day. We celebrate the Immaculate Conception on December 8, nine months before Mary’s birthday on Sept. 8.
The belief that our Lady was conceived without sin existed since the early Church; and Pope Pius IX formally proclaimed it as a dogma of faith in 1854.A dogma is a statement declaring to the world that God has revealed this truth which all men should believe. About 3 years after the declaration, Mary herself confirmed the infallible words of the Pope. She appeared to a young girl named Bernadette at Lourdes, France. When asked who she was, her answer was: I am the Immaculate Conception!
(Reference: “What Is the Immaculate Conception” by Scott Richert; Immaculate Conception and Virgin Birth (The Nazarene Way of Essenic Studies); IneffabilisDeus (Apostolic Constitution issued by Pope Pius IX on December 8, 1854; “God’s Kindness to Mankind” by Pope Pius XII).