"The Feast of the Immaculate Conception
The doctrine of the Immaculate Conception is the doctrine that the Virgin Mary was conceived without original sin, that twist in our nature that makes our will unable to follow what it knows to be right. It was this grace that enabled Mary to give a true and considered “Yes” to the request, conveyed by the Angel Gabriel, that she should consent to be the mother of the incarnate God. The doctrine was almost universally believed over the centuries and but was only formally defined as a doctrine of the Church by Pope Pius IX in 1854. It is one of the Marian doctrines that Islam shares with the Catholic Church."