Polycarp, Vincent of Saragossa, Pancras of Rome, and Saint Chrysogonus at Sant'Apollinare Nuovo in Ravenna.
“‘Sacred Tradition and Sacred Scripture make up a single sacred deposit of the Word of God’ (DV 10) in which, as in a mirror, the pilgrim Church contemplates God, the source of all her riches.” (CCC 97)
One might loosely define tradition as the authoritative and authentic Christian history of theological doctrines and devotional practices. Christianity is fundamentally grounded in the earth-shattering historical events in the life of Jesus Christ (His incarnation, preaching, miracles, passion, crucifixion, resurrection, and ascension).
Eyewitnesses (Lk 1:1-2; Acts 1:1-3; 2 Pet 1:16-18) communicated these true stories to the early Christians, who in turn passed them on to other Christians (under the guidance of the Church's authority) down through the ages. Therefore, Christian tradition, defined as authentic Church history, is unavoidable, and is a very good thing: not a “bad” thing at all.
Many read the accounts of Jesus' conflicts with the Pharisees and get the idea that He was utterly opposed to all tradition whatsoever. This is not true.
A close reading of passages such as Matthew 15:3-9 and Mark 7:8-13 will reveal that He only condemned corrupt traditions of men, not tradition per se. He uses qualifying phrases like “your tradition,” “precepts of men,” “tradition of men,” as opposed to “word of God” or “the commandment of God” and so forth. St. Paul makes exactly the same contrast:
Colossians 2:8 (RSV) See to it that no one makes a prey of you by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the universe, and not according to Christ.
The New Testament explicitly teaches that traditions can be either good (from God) or bad (from men, when against God's true traditions). Corrupt traditions from the Pharisees were bad; though many of their legitimate teachings were recognized by Jesus (see, e.g., Mt 23:3).
The spoken gospel and the apostolic writings (some eventually formulated as Holy Scripture; some not) were altogether good: the authentic Christian tradition as revealed by the incarnate God to the apostles, and “ratified” by the Church.
The Greek word for “tradition” in the New Testament is paradosis. It occurs in Colossians 2:8, and in the following three passages (among others):
1 Corinthians 11:2 . . . maintain the traditions even as I have delivered them to you.
2 Thessalonians 2:15 . . . stand firm and hold to the traditions which you were taught by us, either by word of mouth or by letter.
2 Thessalonians 3:6 . . . the tradition that you received from us.
St. Paul makes no distinction between written and oral tradition. He doesn't regard oral Christian tradition as bad and undesirable. This is made even more clear in two other statements to Timothy:
2 Timothy 1:13 Follow the pattern of the sound words which you have heard from me, . . .
2 Timothy 2:2 and what you have heard from me before many witnesses entrust to faithful men who will be able to teach others also.
St. Paul is here urging Timothy not only to “follow” his oral teaching which “heard from” him, but to also pass it on to others. This is a clear picture of authentic historical continuity of Christian doctrine: precisely what the Catholic Church calls sacred tradition, or, when emphasizing the teaching authority of bishops in the Church, “apostolic succession.”
The phrase “deposit of faith” is also used when describing the original gospel teaching as handed over or delivered to the apostles (see, e.g., Acts 2:42, Jude 3). The Catholic Church considers itself merely the “custodian” or “guardian” of this public revelation or “deposit” from God, because we believe that God set up His Church (Matthew 16), making St. Peter the leader, and that it has continued through history ever since. It's all God's doing, not ours. We participate in His plan by His grace and mercy.
When the first Christians went out and preached the gospel of Jesus Christ after Pentecost, this was an oral tradition. Some of it was recorded in the Bible (e.g., in Acts 2) but most was not, and indeed could not be, for sheer volume (see John 20:30, 21:25). It was primarily this oral Christian tradition that turned the world upside down, not the text of the New Testament (many if not most people couldn't read then anyway).
Accordingly, when the phrases “word of God” or “word of the Lord” occur in Acts and the epistles, they almost always refer to oral preaching, not to the written word of the Bible, as many Protestants (and a lot of Catholics, too) casually assume.
The New Testament itself is a record of primitive, apostolic Christianity. It is a development, so to speak, of both the Old Testament and early oral Christian preaching and teaching and tradition. The process of canonization of the New Testament took over 300 years and involved taking into account human opinions and traditions as to which books were believed to be Scripture. It was not immediately obvious to all Christians (as some foolishly assume or argue).
Many notable Church Fathers accepted books as part of Scripture which are not now so recognized (e.g., The Shepherd of Hermas, the Didache, epistle of Barnabas, 1 Clement). Many others didn't
accept certain canonical books until very late (e.g., Hebrews, James, 2 Peter, and Revelation). Thus, the Bible cannot be separated and isolated from tradition and a developmental process.
In Catholicism, Scripture and tradition are intrinsically interwoven. They have been described as “twin fonts of the one divine well-spring” (revelation), and cannot be separated, any more than can two wings of a bird, two sides of a coin, or two blades of a pair of scissors.
The Church also has strong authority, so that the Catholic rule of faith consists of Scripture, tradition, and the Church. This may be conceived in a word-picture as a “three-legged stool.” If you remove any one of the legs, the stool collapses; all three are equally necessary for it to stand up.
That is Catholicism: and (in case anyone is wondering) all these notions are firmly backed up by Scripture itself, without any contradiction as regards Catholic tradition or Church dogma and doctrine.