The principal theological controversy in the Middle Ages concerning Mary, the mother of Jesus, centred on the
doctrine of the Immaculate Conception. The
doctrine asserts that Mary was preserved free original sin in the first instant of her conception. The theme consistently troubled artists and patrons during the early Renaissance, since no clear
narrative existed for the portrayal of the largely abstract subject.
Although various texts in both the Old and the New Testaments have been cited in defence of the doctrine, it seems to have arisen from a general acceptance in the early church of Mary's holiness. Especially after Mary had been solemnly declared to be the mother of God at the Council of Ephesus in 431, most theologians doubted that one who had been so close to God could have actually committed sinful acts.
The view that Mary had been spared also from the disposition to evil inherent in original sin was not clearly articulated until the 12th century, when considerable debate was centred on an
English celebration of Mary's conception. By the 1380's a clear split had emerged between the Franciscan and Dominican Orders. The discussion was clouded by medieval views of the biological aspects of conception and by a concern that the belief in the universal redemption effected by Jesus should not be threatened.
The latter concern (particularly associated with
St. Thomas Aquinas in the 13th century) was countered not long after by the Franciscan theologian
John Duns Scotus, who argued that Christ's redemptive grace was applied to Mary to prevent sin from reaching her soul and that this special intervention resulted in a more perfect redemption in her case. Mary's privilege, thus, was the result of God's grace and not of any intrinsic merit on her part.
A gradual acceptance of the Franciscans' views over the next several centuries was reflected in the teaching of various popes (especially
Sixtus IV in the late 15th century) and the councils of Basel (1439) and Trent (1546). It was not, however, until December 8, 1854, that Pius IX, urged by the majority of Catholic bishops throughout the world, solemnly declared in the bull
Ineffabilis Deus that the doctrine was revealed by God and hence was to be firmly believed as such by all Catholics. The feast of the Immaculate Conception is celebrated on December 8.