"A church which is not one in its doctrine and faith can never be the True Church … Hence, because truth must be one, of all the different churches … only one can be the true one … and out of that Church there is no salvation. Now, in order to determine which is this one true Church … it is necessary to examine which is the Church first founded by Jesus Christ, for, when this is ascertained, it must be confessed that this one alone is the true Church which, having once been the true Church must always have been the true Church and must forever be the true Church. For to this first Church has been made the promise of the Savior that the gates of Hell would never be able to overturn it (Matthew 16:18) … In the entire history of religion, we find that the Roman Catholic Church alone was the first Church, and that the other false and heretical churches afterwards departed and separated from her. This is the Church which was propagated by the Apostles and afterwards governed by pastors whom the Apostles themselves appointed to rule over her … This character can be found only in the Roman Church, whose pastors descend securely by an uninterrupted and legitimate succession from the Apostles of the world (Matthew 28:20)
"The innovators themselves do not deny that the Roman Church was the first which Jesus Christ founded … however, they say … that it was the true Church until the fifth century, or until … it fell away, because it had been corrupted by the Catholics … But how could that Church fall which St. Paul calls the “pillar and ground of truth” (I Timothy 3:15)? … No. The Church has not failed … The truth is … that all the false churches which have separated from the Roman Church have fallen away and erred … To convince all heretical sects of their error, there is no way more certain and safe than to show that our Catholic Church has been the first one founded by Jesus Christ; for, this being established, it is proved beyond all doubt that ours is the only true Church and that all the others which have left it and separated are certainly in error … But, pressed by this argument, the innovators have invented an answer: they say that the visible Church has failed, but not the invisible Church … But these doctrines are diametrically opposed to the Gospel. "The innovators have been challenged several times to produce a text of Sacred Scripture which would prove the existence of the invisible church they invented, and we are unable to obtain any such text from them. How could they adduce such a text when, addressing His Apostles whom He left as the propagators of His Church, Jesus said: “You cannot be hidden” (Matthew 5:14)? … Thus He has declared that the Church cannot help but be visible to everyone … The Church has been at all times, and will forever be, necessarily visible, so that each person may always be able to learn from his pastor the true doctrine regarding the dogmas of faith … to receive the Sacraments, to be directed in the way of salvation, and to be enlightened and corrected should he ever fall into error. For, were the Church in any time hidden and invisible, to whom would men have recourse in order to learn what they are to believe and to do? … It was necessary that the Church and her pastors be obvious and visible, principally in order that there might be an infallible judge … to resolve all doubts, and to whose decision everyone should necessarily submit. Otherwise, there would be no sure rule of faith by which Christians could know the true dogmas of faith and the true precepts of morality, and among the faithful there would be endless disputes and controversies … “And Christ gave some apostles, and others pastors and doctors, that henceforth we be no more children tossed to-and-fro and carried about with every wind of doctrine” (Eph. 4:11-14) "But what faith can we learn from these false teachers when, in consequence of separating from the Church, they have no rule of faith? … How often Calvin changed his opinions! And, during his life, Luther was constantly contradicting himself: on the single article of the Eucharist, he fell into thirty-three contradictions! A single contradiction is enough to show that they did not have the Spirit of God. “He cannot deny Himself” (II Timothy 2:13). In a word, take away the authority of the Church, and neither Divine Revelation nor natural reason itself is of any use, for each of them may be interpreted by every individual according to his own caprice … Do they not see that from this accursed liberty of conscience has arisen the immense variety of heretical and atheistic sects? … I repeat: if you take away obedience to the Church, there is no error which will not be embraced.