In the Catholic Church tradition, the Blessed Virgin Mary is not only the mother of Christ but also the mother of the Church itself. Mary's veneration has occurred over time, particularly since the Middle Ages. The doctrine of Immaculate Conception claims Mary was conceived without original sin, while the doctrine of Perpetual Virginity states Mary remained a virgin throughout life. She is known as the protector of Christians. In the 18th century, Saint Alphonsus described Mary as the 'Gate of Heaven', a notion reinforced in more recent times by Pope John Paul II's Redemptoris Mater. Mary is celebrated in the liturgical calendar with feast days that are considered more significant than those of the saints.