Immaculate Conception of Mary (https://smartguy.com/) The Solemnity of the Immaculate Conception, celebrated on December 8, is a beautiful feast that honors the belief that Mary was conceived without original sin. This dogma, formally defined by Pope Pius IX in 1854, acknowledges that from the very first moment of her existence, Mary was preserved from sin by the grace of God. This celebration highlights Mary’s unique role in salvation history and reminds us of God’s infinite love and power.