It is a fact of history, scripture and tradition that Our Lord Jesus Christ founded His universal Church (the Catholic Church) upon St. Peter.
Matthew 16:18-19-“And I say to thee: That thou art Peter: and upon this rock I will build my Church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven.”
Our Lord made St. Peter the first pope, entrusted to him His entire flock, and gave him supreme authority in the universal Church of Christ.
John 21:15-17-“Jesus saith to Simon Peter: Simon, son of John, lovest thou me? He saith to him: Yea, Lord, thou knowest that I love thee. He saith to him: Feed my lambs. He saith to him again: Simon, son of John, lovest thou me? He saith to him: Yea, Lord, thou knowest that I love thee. He saith to him: Feed my lambs. He saith to him a third time: Simon, son of John, lovest thou me? Peter was grieved, because he had said to him the third time: Lovest thou me? And he said to him: Lord, thou knowest all things: thou knowest that I love thee. He said to him: Feed my sheep.”
And with the supreme authority that Our Lord Jesus Christ conferred upon St. Peter (and his successors, the popes) comes what is called Papal Infallibility. Papal Infallibility is inseparable from Papal Supremacy – there was no point for Christ to make St. Peter the head of His Church (as Christ clearly did) if St. Peter or his successors, the popes, could err when exercising that supreme authority to teach on a point of Faith. The supreme authority must be unfailing on binding matters of Faith and morals or else it is no true authority from Christ at all.
Papal Infallibility does not mean that a pope cannot err at all and it does not mean that a pope cannot lose his soul and be damned in Hell for grave sin. It means that the successors of St. Peter (the popes of the Catholic Church) cannot err when authoritatively teaching on a point of Faith or morals to be held by the entire Church of Christ. We find the promise of the unfailing faith for St. Peter and his successors referred to by Christ in Luke 22.
Luke 22:31-32- “And the Lord said: Simon, Simon, behold Satan hath desired to have all of you, that he may sift you as wheat: But I have prayed for thee, that thy faith fail not: and thou, being once converted, confirm thy brethren.”
Satan desired to sift all the Apostles (plural) like wheat, but Jesus prayed for Simon Peter (singular), that his faith fail not. Jesus is saying that St. Peter and his successors (the popes of the Catholic Church) have an unfailing faith when authoritatively teaching a point of faith or morals to be held by the entire Church of Christ.
Pope Pius IX, Vatican Council I, 1870, ex cathedra:
“SO, THIS GIFT OF TRUTH AND A NEVER FAILING FAITH WAS DIVINELY CONFERRED UPON PETER AND HIS SUCCESSORS IN THIS CHAIR…”
Pope Pius IX, Vatican Council I, 1870, ex cathedra:
“… the See of St. Peter always remains unimpaired by any error, according to the divine promise of our Lord the Savior made to the chief of His disciples: ‘I have prayed for thee [Peter], that thy faith fail not ...’”
And this truth has been held since the earliest times in the Catholic Church.
Pope St. Gelasius I, epistle 42, or Decretal de recipiendis et non recipiendis libris, 495: “Accordingly, the see of Peter the Apostle of the Church of Rome is first, having neither spot, nor wrinkle, nor anything of this kind (Eph. 5:27).”
The promise of Christ to St. Peter that his faith cannot fail (i.e., is indefectible) presupposes that Peter’s faith – and the office Jesus establishes in Peter – is infallible. For that which is unfailing in matters of faith must be infallible. Papal Infallibility is therefore directly connected to Christ’s promise to St. Peter (and his successors) in Luke 22 concerning Peter’s unfailing Faith. Papal Infallibility is also found in Christ’s promise to Peter in Matthew 16. Jesus declares that whatever Peter binds (i.e., whatever he declares must be held by the universal Church) is also bound in Heaven. Since Heaven cannot bind error, the things St. Peter and his successors bind on the universal Church must always be true. That’s infallibility. Although this truth was believed since the beginning of the Church, it was specifically defined as a dogma at the First Vatican Council in 1870.
Pope Pius IX, Vatican Council I, 1870, Session 4, Chap. 4: “…the Roman Pontiff, when he speaks ex cathedra [from the Chair of Peter], that is, when carrying out the duty of the pastor and teacher of all Christians in accord with his supreme apostolic authority he explains a doctrine of faith or morals to be held by the universal Church... operates with that infallibility with which the divine Redeemer wished that His Church be instructed in defining doctrine on faith and morals; and so such definitions of the Roman Pontiff from himself, but not from the consensus of the Church, are unalterable.”
But how does one know when a pope is exercising his unfailing Faith to infallibly teach from the Chair of St. Peter? The answer is that we know from the language that the pope uses or the manner in which the pope teaches. Vatican I defined two requirements which must be fulfilled: 1) when the pope is carrying out his duty as pastor and teacher of all Christians in accord with his supreme apostolic authority; 2) when he explains a doctrine on faith or morals to be held by the entire Church of Christ. A pope can fulfill both of these requirements in just one line, by anathematizing a false opinion (such as many dogmatic councils) or by saying “By our apostolic authority we declare…” or by saying “We believe, profess, and teach” or by using words of similar importance and meaning, which indicate that the pope is teaching the whole Church on Faith in a definitive and binding fashion.
So, when a pope teaches from the Chair of Peter in the manner stipulated above he cannot be wrong. If he could be wrong, then the Church of Christ could be officially led into error, and Christ’s promise to St. Peter and His Church would fail (which is impossible). That which is taught from the Chair of Peter by the popes of the Catholic Church is the teaching of Jesus Christ Himself. To reject that which is taught by the popes from the Chair of Peter is simply to despise Jesus Christ Himself.
Luke 10:16- “He that heareth you, heareth me: and he that despiseth you despiseth me…”
Matthew 18:17 -“And if he will not hear the church, let him be to thee as the heathen and publican.”
Pope Leo XIII, Satis Cognitum, 1896:
“… Christ instituted a living, authoritative and permanent Magisterium… If it could in any way be false, an evident contradiction follows; for then God Himself would be the author of error in man.”
THE CHAIR OF PETER SPEAKS THE TRUTH THAT CHRIST HIMSELF DELIVERED
The truths of faith which have been proclaimed by the popes speaking infallibly from the Chair of Peter are called dogmas. The dogmas make up what is called the deposit of Faith. And the deposit of Faith ended with the death of the last apostle.
Pope St. Pius X, Lamentabile, The Errors of the Modernists #21: “Revelation, constituting the object of Catholic faith, was not completed with the apostles.” - Condemned
This means that when a pope defines a dogma from the Chair of Peter he does not make the dogma true, but rather he proclaims what is already true, what has already been revealed by Christ and delivered to the Apostles. The dogmas are therefore unchangeable, of course. One of these dogmas in the deposit of Faith is that Outside the Catholic Church There is No Salvation. Since this is the teaching of Jesus Christ, one is not allowed to dispute this dogma or to question it; one must simply accept it. It does not matter if one doesn’t like the dogma, doesn’t understand the dogma, or doesn’t see justice in the dogma. If one doesn’t accept it as infallibly true then one simply does not accept Jesus Christ, because the dogma comes to us from Jesus Christ.
Pope Leo XIII, Satis Cognitum (# 9), June 29, 1896:
“… can it be lawful for anyone to reject any one of those truths without by that very fact falling into heresy? – without separating himself from the Church? – without repudiating in one sweeping act the whole of Christian teaching? For such is the nature of faith that nothing can be more absurd than to accept some things and reject others. Faith, as the Church teaches, is that supernatural virtue by which… we believe what He has revealed to be true, not on account of the intrinsic truth perceived by the natural light of human reason [author: that is, not because it seems correct to us], but because of the authority of God Himself, the Revealer, who can neither deceive nor be deceived… But he who dissents even in one point from divinely revealed truth absolutely rejects all faith, since he thereby refuses to honor God as the supreme truth and the formal motive of faith.”
Those who refuse to believe in the dogma Outside the Church There is No Salvation until they understand how there is justice in it are simply withholding their Faith in Christ’s revelation. Those with the true Faith in Christ (and His Church) accept His teaching first and understand the truth in it (i.e., why it is true) second. A Catholic does not withhold his belief in Christ’s revelation until he can understand it. That is the mentality of a faithless heretic who possesses insufferable pride. St. Anselm sums up the true Catholic outlook on this point.
St. Anselm, Doctor of the Church, Prosologion, Chap. 1: “For I do not seek to understand that I may believe, but I believe in order to understand. For this also I believe, that unless I believed, I should not understand.”
Romans 11:33-34- “O the depth of the riches of the wisdom and of the knowledge of God! How incomprehensible are his judgments, and how unsearchable his ways! For who hath known the mind of the Lord? Or who hath been his counselor? Or who hath first given to him, and recompense shall be made him?”
Isaias 55:8-9- “For my thoughts are not your thoughts: nor your ways my ways, saith the Lord. For as the heavens are exalted above the earth, so are my ways exalted above your ways, and my thoughts above your thoughts.”
 Denzinger 1837.
 Denzinger 1836.
 Denzinger 163.
 Denzinger 1839.
 The Papal Encyclicals, by Claudia Carlen, Raleigh: The Pierian Press, 1990,Vol. 2 (1878-1903), p. 394.
 Denzinger 2021.
 The Papal Encyclicals, Vol. 2 (1878-1903), p. 394.
 Fr. Christopher Rengers, The 33 Doctors of the Church, Rockford: IL, Tan Books, 2000, p. 273.
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