Is the Bible the sole rule of faith for Christians, or does Tradition also provide a norm for believers? Let's see what the Fathers of the Church and other early Christian writers had to say.
"As I said before, the Church, having received this preaching and this faith, although she is disseminated throughout the whole world, yet guarded it, as if she occupied but one house. She likewise believes these things just as if she had but one soul and one and the same heart; and harmoniously she proclaims them and teaches them and hands them down, as if she possessed but one mouth. For, while the languages of the world are diverse, nevertheless, the authority of the tradition is one and the same." (Against Heresies 1, 10:2 [A.D. 180]).
"That is why it is surely necessary to avoid them, while cherishing with the utmost diligence the things pertaining to the Church, and to lay hold of the tradition of truth. . . . What if the apostles had not in fact left writings to us? Would it not be necessary to follow the order of tradition, which was handed down to those to whom they entrusted the Churches?" (Against Heresies, 3, 4:1 [A.D. 180]).
"It is possible, then, for everyone in every church, who may wish to know the truth, to contemplate the tradition of the apostles which has been made known throughout the whole world. And we are in a position to enumerate those who were instituted bishops by the apostles and their successors to our own times: men who neither knew nor taught anything like these heretics rave about.
"But since it would be too long to enumerate in such a volume as this the successions of all the churches, we shall confound all those who, in whatever manner, whether through self-satisfaction or vainglory, or through blindness and wicked opinion, assemble other than where it is proper, by pointing out here the successions of the bishops of the greatest and most ancient church known to all, founded and organized at Rome by the two most glorious apostles, Peter and Paul, that church which has the tradition and the faith which comes down to us after having been announced to men by the apostles.
"With this church, because of its superior origin, all churches must agree--that is, all the faithful in the whole world--and it is in her that the faithful everywhere have maintained the apostolic tradition." (Against Heresies, 3, 3:1-2 [A.D. 180]).
"Although there are many who believe that they themselves hold to the teachings of Christ, there are yet some among them who think differently from their predecessors. The teaching of the Church has indeed been handed down through an order of succession from the apostles and remains in the churches even to the present time. That alone is to be believed as the truth which is in no way at variance with ecclesiastical and apostolic tradition." (Fundamental Doctrines 1, Pref., 2 [A.D. 220-230]).
"Of the dogmas and kerygmas preserved in the Church, some we possess from written teaching and others we receive from the tradition of the apostles, handed on to us in mystery. In respect to piety both are of the same force. No one will contradict any of these, no one, at any rate, who is even moderately versed in matters ecclesiastical. Indeed, were we to try to reject unwritten customs as having no great authority, we would unwittingly injure the gospel in its vitals; or rather, we would reduce kerygma to a mere term." (The Holy Spirit, 27, 66 [A.D. 375]).
"It is needful also to make use of tradition, for not everything can be gotten from Sacred Scripture. The holy apostles handed down some things in the Scriptures, other things in tradition." (Panacea Against All Heresies, 61, 6 [A.D. 374]).
" 'Therefore, brethren, stand fast and hold the traditions which you have been taught, whether by word or by our letter.' From this it is clear that they did not hand down everything by letter, but there is much also that was not written. Like that which was written, the unwritten too is worthy of belief. So let us regard the tradition of the Church also as worthy of belief. Is it a tradition? Seek no further" (Homilies on the Second Epistle to the Thessalonians [A.D. 398-404]).
"But in regard to those observances which we carefully attend and which the whole world keeps, and which derive not from Scripture but from tradition, we are given to understand that they are recommended and ordained to be kept, either by the apostles themselves or by plenary councils, the authority of which is quite vital in the Church" (Letter to Januarius [A.D. 400]).
"If you should find someone who does not yet believe in the gospel, what would you answer him when he says: 'I do not believe'? Indeed, I would not believe in the gospel myself if the authority of the Catholic Church did not influence me to do so" (Against the Letter of Mani [A.D. 397]).
Vincent of Lerins
"With great zeal and closest attention, therefore, I frequently inquired of many men, eminent for their holiness and doctrine, how I might, in a concise and, so to speak, general and ordinary way, distinguish the truth of the Catholic faith from the falsehood of heretical depravity.
"I received almost always the same answer from all of them, that if I or anyone else wanted to expose the frauds and escape the snares of the heretics who rise up and to remain intact and in a sound faith, it would be necessary, with the help of the Lord, to fortify that faith in a twofold manner: first, of course, by the authority of divine law; and then by the tradition of the Catholic Church.
"Here, perhaps, someone may ask: 'If the canon of the Scriptures be perfect and in itself more than suffices for everything, why is it necessary that the authority of ecclesiastical interpretation be joined to it?' Because, quite plainly, Sacred Scripture, by reason of its own depth, is not accepted by everyone as having one and the same meaning. . . .
"Thus, because of so many distortions of such various errors, it is highly necessary that the line of prophetic and apostolic interpretation be directed in accord with the norm of the ecclesiastical and Catholic meaning. In the Catholic Church herself every care must be taken that we hold fast to that which has been believed everywhere, always, and by all. For this is, then, truly and properly Catholic" (The Notebooks [A.D. 434]).