Chapter 4.
On the infallible teaching authority of the Roman Pontiff
1. That apostolic primacy which the Roman Pontiff possesses as successor of Peter, the prince of the apostles, includes also the supreme power of teaching. This Holy See has always maintained this, the constant custom of the Church demonstrates it, and the ecumenical councils, particularly those in which East and West met in the union of faith and charity, have declared it.
2. So the fathers of the fourth Council of Constantinople, following the footsteps of their predecessors, published this solemn profession of faith: The first condition of salvation is to maintain the rule of the true faith. And since that saying of our lord Jesus Christ, You are Peter, and upon this rock I will build my Church [55], cannot fail of its effect, the words spoken are confirmed by their consequences. For in the Apostolic See the Catholic religion has always been preserved unblemished, and sacred doctrine been held in honor. Since it is our earnest desire to be in no way separated from this faith and doctrine, we hope that we may deserve to remain in that one communion which the Apostolic See preaches, for in it is the whole and true strength of the Christian religion [56].
What is more, with the approval of the second Council of Lyons, the Greeks made the following profession:
“The Holy Roman Church possesses the supreme and full primacy and principality over the whole Catholic Church. She truly and humbly acknowledges that she received this from the Lord himself in blessed Peter, the prince and chief of the apostles, whose successor the Roman Pontiff is, together with the fullness of power. And since before all others she has the duty of defending the truth of the faith, so if any questions arise concerning the faith, it is by her judgment that they must be settled.” [57]
Then there is the definition of the Council of Florence:
“The Roman Pontiff is the true vicar of Christ, the head of the whole Church and the father and teacher of all Christians; and to him was committed in blessed Peter, by our lord Jesus Christ, the full power of tending, ruling and governing the whole Church.” [58]
3. To satisfy this pastoral office, our predecessors strove unwearyingly that the saving teaching of Christ should be spread among all the peoples of the world; and with equal care they made sure that it should be kept pure and uncontaminated wherever it was received.
4. It was for this reason that the bishops of the whole world, sometimes individually, sometimes gathered in synods, according to the long established custom of the Churches and the pattern of ancient usage referred to this Apostolic See those dangers especially which arose in matters concerning the faith. This was to ensure that any damage suffered by the faith should be repaired in that place above all where the faith can know no failing [59].