...AND PROTECTS HIS CHURCH FROM TEACHING ERROR IN FAITH ANDMORALS
Infallibility is the protection given by the Holy Spirit to the pope so that he will never teach error in matters of faith and morals. The First Vatican Council, which defined papal infallibility in 1870, was acting in response to a challenge to the doctrine which has always been true and was accepted and practiced from the earliest times. The evidence for papal infallibility comes from three sources: Scripture, history and logic.
First, Scripture clearly shows that Christ intended a special role for Peter in the establishment of the Church, and special divine protection for Peter in the exercise of his authority. This is evidenced in passages such as: "Thou art Peter and upon this rock I will build my Church and the powers of hell will not prevail against it...to you I give the keys to the Kingdom of Heaven and whatever you bind on earth is bound in heaven; whatever you loose on earth is loosed in heaven." (Matthew 16:17-19); "Do you love me, Peter... Feed my sheep." (John 21:15-17); and "I have prayed for you, Peter, that your faith may not fail. You in turn must confirm your brethren." (Luke 22:31-32)
Second, history shows that from the earliest times the bishops of Rome acted as if they had special authority in succession from St. Peter, and the rest of the Church accepted their authority as if they knew it was genuine. Thus Pope Clement wrote to settle a problem in the Church of Corinth before the end of the 1st century. The Church Fathers, too, repeatedly attest to the authority of the Roman See. And the Popes always had the decisive word at general councils, as when the Fathers of the Council of Chalcedon in 451 A.D. accepted the Papal definition of the two natures of Christ and said, "Peter has spoken through Leo."
Third, logic tells us that since Peter had a special commission and special powers from Christ, these powers must be essential to the Church. If these special and essential powers were to pass out of existence, it would be proof that Christ was no longer with His Church and that the "powers of Hell" had indeed prevailed. Since Christ knew that Peter would not live until the end of time, he must have intended that the successors to Peter have these powers.
Since the successors of Peter have the same authority, which comes ultimately from Christ, to bind and loose, they have the authority to bind the faithful in matters pertaining to salvation that is, in faith or morals. If a Pope could bind the faithful to error, it would be a clear triumph of the powers of Hell, because the entire Church would be bound to follow the error under Christ's own authority. Therefore, the logic of the situation demands that Peter's power of confirming the brethren must be an infallible power.
Vatican I clarified what was at that time a confusing issue, but did so by way of stating clearly what Christ's teaching was, not by way of adding anything new. Vatican I therefore carefully enumerated the conditions under which the Pope is in fact infallible the same conditions which logic demands, which Scripture suggests, and which tradition shows us in action down through the centuries.
When the Pope (1) intends to teach (2) by virtue of his supreme authority (3) on a matter of faith and morals (4) to the whole Church, he is protected by the Holy Spirit from error. His teaching act is therefore called "infallible" and the teaching which he articulates is termed "irreformable" which means it can never be changed because it is certainly true.
Jeffrey A. Mirus holds a Ph.D. in History of Theology