9 The Church, founded on these principles and mindful of her office, has done nothing with greater zeal and endeavour than she has displayed in guarding the integrity of the faith. Hence she regarded as rebels and expelled from the ranks of her children all who held beliefs on any point of doctrine different from her own. The Arians, the Montanists, the Novatians, the Quartodecimans, the Eutychians, did not certainly reject all Catholic doctrine: they abandoned only a tertian portion of it. Still who does not know that they were declared heretics and banished from the bosom of the Church? In like manner were condemned all authors of heretical tenets who followed them in subsequent ages. "There can be nothing more dangerous than those heretics who admit nearly the whole cycle of doctrine, and yet by one word, as with a drop of poison, infect the real and simple faith taught by our Lord and handed down by Apostolic tradition" (Auctor Tract . de Fide Orthodoxa contra Arianos ). The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium. Epiphanius, Augustine, Theodoret, drew up a long list of the heresies of their times. St. Augustine notes that other heresies may spring up, to a single one of which, should any one give his assent, he is by the very fact cut off from Catholic unity. "No one who merely disbelieves in all (these heresies) can for that reason regard himself as a Catholic or call himself one. For there may be or may arise some other heresies, which are not set out in this work of ours, and, if any one holds to one single one of these he is not a Catholic" (S. Augustinus, De Haeresibus , n. 88). The need of this divinely instituted means for the preservation of unity, about which we speak is urged by St. Paul in his epistle to the Ephesians. In this he first admonishes them to preserve with every care concord of minds: "Solicitous to keep the unity of the Spirit in the bond of peace" ( Eph . iv., 3, et seq .). And as souls cannot be perfectly united in charity unless minds agree in faith, he wishes all to hold the same faith: "One Lord, one faith," and this so perfectly one as to prevent all danger of error: "that henceforth we be no more children, tossed to and fro, and carried about with every wind of doctrine by the wickedness of men, by cunning craftiness, by which they lie in wait to deceive" ( Eph . iv., 14): and this he teaches is to be observed, not for a time only-"but until we all meet in the unity of faith...unto the measure of the age of the fulness of Christ" (13). But, in what has Christ placed the primary principle, and the means of preserving this unity? In that-"He gave some Apostles-and other some pastors and doctors, for the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ" (11-12). Wherefore, from the very earliest times the fathers and doctors of the Church have been accustomed to follow and, with one accord to defend this rule. Origen writes: "As often as the heretics allege the possession of the canonical scriptures, to which all Christians give unanimous assent, they seem to say: `Behold the word of truth is in the houses.' But we should believe them not and abandon not the primary and ecclesiastical tradition. We should believe not otherwise than has been handed down by the tradition of the Church of God" ( Vetus Interpretatio Commentariorum in Matt . n. 46). Irenaeus too says: "The doctrine of the Apostles is the true faith...which is known to us through the Episcopal succession...which has reached even unto our age by the very fact that the Scriptures have been zealously guarded and fully interpreted" ( Contra Haereses , lib. iv., cap. 33, n. 8). And Tertullian: "It is therefore clear that all doctrine which agrees with that of the Apostolic churches - the matrices and original centres of the faith, must be looked upon as the truth, holding without hesitation that the Church received it from the Apostles, the Apostles from Christ and Christ from God....We are in communion with the Apostolic churches, and by the very fact that they agree amongst themselves we have a testimony of the truth" ( De Praescrip ., cap. xxxi). And so Hilary: "Christ teaching from the ship signifies that those who are outside the Church can never grasp the divine teaching; for the ship typifies the Church where the word of life is deposited and preached. Those who are outside are like sterile and worthless sand: they cannot comprehend" ( Comment. in Matt . xiii., n. I). Rufinus praises Gregory of Nazianzum and Basil because "they studied the text of Holy Scripture alone, and took the interpretation of its meaning not from their own inner consciousness, but from the writings and on the authority of the ancients, who in their turn, as it is clear, took their rule for understanding the meaning from the Apostolic succession" ( Hist. Eccl ., lib. ii., cap. 9). Wherefore, as appears from what has been said, Christ instituted in the Church a living , authoritative and permanent Magisterium , which by His own power He strengthened, by the Spirit of truth He taught, and by miracles confirmed. He willed and ordered, under the gravest penalties, that its teachings should be received as if they were His own. As often, therefore, as it is declared on the authority of this teaching that this or that is contained in the deposit of divine revelation, it must be believed by every one as true. If it could in any way be false, an evident contradiction follows; for then God Himself would be the author of error in man. "Lord, if we be in error, we are being deceived by Thee" (Richardus de S. Victore, De Trin ., lib. i., cap. 2). In this wise, all cause for doubting being removed, can it be lawful for anyone to reject any one of those truths without by the 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, through the help of God and through the assistance of His grace, we believe what he has revealed to be true, not on account of the intrinsic truth perceived by the natural light of reason, but because of the authority of God Himself, the Revealer, who can neither deceive nor be deceived" (Conc. Vat., Sess. iii., cap. 3). If then it be certain that anything is revealed by God, and this is not believed, then nothing whatever is believed by divine Faith: for what the Apostle St. James judges to be the effect of a moral deliquency, the same is to be said of an erroneous opinion in the matter of faith. "Whosoever shall offend in one point, is become guilty of all" (Ep. James ii., 10). Nay, it applies with greater force to an erroneous opinion. For it can be said with less truth that every law is violated by one who commits a single sin, since it may be that he only virtually despises the majesty of God the Legislator. But he who dissents even in one point from divinely revealed truth absolutely rejects all faith, since he thereby refuses to honour God as the supreme truth and the formal motive of faith . "In many things they are with me, in a few things not with me; but in those few things in which they are not with me the many things in which they are will not profit them" (S. Augustinus in Psal. liv., n. 19). And this indeed most deservedly; for they, who take from Christian doctrine what they please, lean on their own judgments, not on faith; and not "bringing into captivity every understanding unto the obedience of Christ" (2 Cor . x., 5), they more truly obey themselves than God. "You, who believe what you like, believe yourselves rather than the gospel" (S. Augustinus, lib. xvii., Contra Faustum Manichaeum , cap. 3). For this reason the Fathers of the Vatican Council laid down nothing new, but followed divine revelation and the acknowledged and invariable teaching of the Church as to the very nature of faith, when they decreed as follows: "All those things are to be believed by divine and Catholic faith which are contained in the written or unwritten word of God, and which are proposed by the Church as divinely revealed, either by a solemn definition or in the exercise of its ordinary and universal Magisterium" (Sess. iii., cap. 3). Hence, as it is clear that God absolutely willed that there should be unity in His Church, and as it is evident what kind of unity He willed, and by means of what principle He ordained that this unity should be maintained, we may address the following words of St. Augustine to all who have not deliberately closed their minds to the truth: "When we see the great help of God, such manifest progress and such abundant fruit, shall we hesitate to take refuge in the bosom of that Church, which, as is evident to all, possesses the supreme authority of the Apostolic See through the Episcopal succession? In vain do heretics rage round it; they are condemned partly by the judgment of the people themselves, partly by the weight of councils, partly by the splendid evidence of miracles. To refuse to the Church the primacy is most impious and above measure arrogant. And if all learning, no matter how easy and common it may be, in order to be fully understood requires a teacher and master, what can be greater evidence of pride and rashness than to be unwilling to learn about the books of the divine mysteries from the proper interpreter, and to wish to condemn them unknown?" ( De Unitate Credendi , cap. xvii., n. 35). It is then undoubtedly the office of the church to guard Christian doctrine and to propagate it in its integrity and purity. But this is not all: the object for which the Church has been instituted is not wholly attained by the performance of this duty. For, since Jesus Christ delivered Himself up for the salvation of the human race, and to this end directed all His teaching and commands, so He ordered the Church to strive, by the truth of its doctrine, to sanctify and to save mankind. But faith alone cannot compass so great, excellent, and important an end. There must needs be also the fitting and devout worship of God, which is to be found chiefly in the divine Sacrifice and in the dispensation of the Sacraments, as well as salutary laws and discipline. All these must be found in the Church, since it continues the mission of the Saviour for ever. The Church alone offers to the human race that religion-that state of absolute perfection - which He wished, as it were, to be incorporated in it. And it alone supplies those means of salvation which accord with the ordinary counsels of Providence.
Source: Satis Cognitum (Vatican.va)