The mere fact that the infallible New Testament books were selected by the Catholic Church's early fathers (Sacred Scripture that even Protestant denominations read and believe), confirms the infallible authority of the Church.
From the Catholic Encyclopedia:
"Scriptures for proof of the Church's infallible authority we appeal to them merely as reliable historical sources, and abstract altogether from their inspiration. Even considered as purely human documents they furnish us, we maintain, with a trustworthy report of Christ's sayings and promises; and, taking it to be a fact that Christ said what is attributed to Him in the Gospels, we further maintain that Christ's promises to the Apostles and their successors in the teaching office include the promise of such guidance and assistance as clearly implies infallibility. Having thus used the Scriptures as mere historical sources to prove that Christ endowed the Church with infallible teaching authority it is no vicious circle, but a perfectly legitimate logical procedure, to rely on the Church's authority for proof of what writings are inspired.
Merely remarking for the present that the texts in which Christ promised infallible guidance especially to Peter and his successors in the primacy might be appealed to here as possessing an a fortiori value, it will suffice to consider the classical texts usually employed in the general proof of the Church's infallibility; and of these the principal are:
•John 14, 15, and 16;
•I Timothy 3:14-15; and
•Acts 15:28 sq.
In Matthew 28:18-20, we have Christ's solemn commission to the Apostles delivered shortly before His Ascension: "All power is given to me in heaven and in earth. Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost; teaching them to observe all things whatsoever I have commanded you: and behold I am with you all days, even to the consummation of the world." In Mark 16:15-16, the same commission is given more briefly with the added promise of salvation to believers and the threat of damnation for unbelievers; "Go ye into the whole world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be condemned."
Now it cannot be denied by anyone who admits that Christ established a visible Church at all, and endowed it with any kind of effective teaching authority, that this commission, with all it implies, was given not only to the Apostles personally for their own lifetime, but to their successors to the end of time, "even to the consummation of the world". And assuming that it was the omniscient Son of God Who spoke these words, with a full and clear realization of the import which, in conjunction with His other promises, they were calculated to convey to the Apostles and to all simple and sincere believers to the end of time, the only reasonable interpretation to put upon them is that they contain the promise of infallible guidance in doctrinal teaching made to the Apostolic College in the first instance and then to the hierarchical college that was to succeed it.
In the first place it was not without reason that Christ prefaced His commission by appealing to the fullness of power He Himself had received: "All power is given to me", etc. This is evidently intended to emphasize the extraordinary character and extent of the authority He is communicating to His Church — an authority, it is implied, which He could not personally communicate were not He Himself omnipotent. Hence the promise that follows cannot reasonably be understood of ordinary natural providential guidance, but must refer to a very special supernatural assistance.
In the next place there is question particularly in this passage of doctrinal authority — of authority to teach the Gospel to all men — if Christ's promise to be with the Apostles and their successors to the end of time in carrying out this commission means that those whom they are to teach in His name and according to the plenitude of the power He has given them are bound to receive that teaching as if it were His own; in other words they are bound to accept it as infallible. Otherwise the perennial assistance promised would not really be efficacious for its purpose, and efficacious Divine assistance is what the expression used is clearly intended to signify. Supposing, as we do, that Christ actually delivered a definite body of revealed truth, to be taught to all men in all ages, and to be guarded from change or corruption by the living voice of His visible Church, it is idle to contend that this result could be accomplished effectively — in other words that His promise could be effectively fulfilled unless that living voice can speak infallibly to every generation on any question that may arise affecting the substance of Christ's teaching.
Without infallibility there could be no finality regarding any one of the great truths which have been identified historically with the very essence of Christianity; and it is only with those who believe in historical Christianity that the question need be discussed. Take, for instance, the mysteries of the Trinity and Incarnation. If the early Church was not infallible in her definitions regarding these truths, what compelling reason can be alleged today against the right to revive the Sabellian, or the Arian, or the Macedonian, or the Apollinarian, or the Nestorian, or the Eutychian controversies, and to defend some interpretation of these mysteries which the Church has condemned as heretical? "
One may not appeal to the inspired authority of the Scriptures, since for the fact of their inspiration the authority of the Church must be invoked, and unless she be infallible in deciding this one would be free to question the inspiration of any of the New Testament writings
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