The Roman Catholic doctrine that ecumenical councils of bishops and the pope speaking ex cathedra are immune from error when teaching concerning faith and morals. The need for infallibility in the church has been argued in recent times from two standpoints. First, since the Holy Spirit indwells the church, it is to be expected that He will ensure that the shepherds of the flock will understand and teach aright the divine message of salvation. Second, since eternal punishment is threatened to those who disobey the Gospel (Mark 16:16), it is to be expected that God will provide a correct understanding of the Gospel in the world.

The infallibility of the pope was first defined by Vatican I* on the basis of such passages as Matthew 16:18; Luke 22:31; John 21:15-understood in the light of their interpretation in the West from early times. Cardinal Cullen composed the definition, making much use of Reginald Pole's De Summo Pontifice (1569). Infallibility is understood as a charisma, given by the Holy Spirit for the preserving and expounding of divine truth. The teaching of previous councils (Constantinople IV, Lyons, and Florence) is referred to as pointing to this conclusion. Vatican II* reaffirmed the doctrine of papal infallibility, but set it in a larger context. The charisma belongs to the pope insofar as he is the head of the college of bishops; when he speaks ex cathedra he has this authority in a special way (singulariter). The extent of the infallibility of bishops in council, and the pope pronouncing ex cathedra, is declared to be “as wide as the divine deposit of faith, which is to be kept as a sacred trust and faithfully expounded.” Roman Catholic theologians also speak of the infallibility of the body of the faithful insofar as it maintains its faith and practice.

Protestants have always opposed this doctrine, arguing that only God and His Word are infallible.

G. Salmon, The Infallibility of the Church (1888); T.G. Jalland, The Church and the Papacy (1944); b.c. Butler, The Church and Infallibility (1954); O. Rousseau, L'Infallibilité de l'église (1962); O. Karrer, Peter and the Church (1963).