Source: A Catholic Response
I commend you because you remember me in everything and maintain the traditions even as I have delivered them to you. 1 Corinthians 11:2
Most Protestant Christians believe that the Bible is the only source concerning faith. According to them, there is no need for Apostolic Tradition or an authoritative, teaching Church. All that they need is the Bible in order to learn about the faith and to live a Christian life. The "Bible Alone" teaching can be appealing in its simplicity, but it suffers from fundamental problems. A few are considered here.
First the Bible itself states that not everything important to the Christian faith is recorded in it. For example, not everything that Christ did is recorded in the inspired Books:
But there are also many other things which Jesus did; were every one of them to be written, I suppose that the world itself could not contain the books that would be written. [John 21:25; RSV]
According to John 20:31, some things have been recorded in the Gospel in order to come to know Christ; however, John 21:25 suggests that there is still more to know about Him. At least for St. John the Apostle, there was more that he needed to teach which was not recorded in the Bible:
I had much to write you, but I would rather not write with pen and ink; I hope to see you soon, and we will talk together face to face. [3 John 13-14]
Also St. Paul instructs Timothy on how to orally pass on the teachings of the faith:
...what you have heard from me before many witnesses entrust to faithful men who will be able to teach others also. [2 Tim. 2:2]
St. Paul even commands (2 Thess. 3:6) the Thessalonian Christians to follow the oral Traditions of the Apostles:
So then, brethren, stand firm and hold to the traditions which you were taught by us (Apostles), either by word of mouth (oral) or by letter (Epistle). [2 Thess. 2:15]
These commands promoting Oral Tradition would be quite strange, if only the Bible were needed to pass on the entire Christian faith.
A second problem with the "Bible Alone" teaching is canonicity - i.e. which Books belong in the Bible? It must be remembered that the Books of the Bible were written individually along with other religious books. Centuries later the Church compiled together the inspired Books under one cover to form the "Bible." A big question in the early Church was which books are the inspired written Word of God. (Inspired=written by men but authored by God; See Catechism of the Catholic Church 106.)
Scripture did not come with an "inspired" Table of Contents. Nowhere in the sacred texts are all the Books listed. There are some Books cited in the sacred writings but these lists are vague and incomplete (Acts 28:23; 2 Peter 3:16). There are also references to books not found in the Bible, such as St. Paul's Epistle to the Laodiceans (Col. 4:16). St. Paul even encourages the Colossians to read this epistle, but still it is not in the Bible. Jesus in the Gospel never attempts to list the "official" Books of the Old Testament (OT). This issue was hotly debated in His day. Today Protestant and Catholic Christians disagree over which Books belong in the OT. Catholics follow the list in the Septuagint (2nd century B.C. Greek translation of the Hebrew Scripture) while Protestants follow the list used by the Pharisees. A list from Jesus could have eliminated this problem, but no such list is found in the Gospel. As a result the Bible needs a visible authority outside of itself to list the inspired sacred Books. This authority must be guided by the Holy Spirit since these Books are from the Holy Spirit.
Some Christians claim that the Table of Contents in their Bible lists the inspired Books. Even though found in modern Bibles, the Table of Contents is still not inspired. It is not the Word of God but words added later by human editors, much similar to footnotes. The Table of Contents is basically the opinion of the publishing editor. Others may claim that the closing verses in the Book of Revelation, specifically Rev. 22:18-19, cap off the Bible and define all the preceding Books as inspired by God. But do these verses apply to the whole Bible or only the Book of Revelation? Another flaw with this idea is that not all Bibles have the same number of Books. As alluded to above, Catholic and Protestant Bibles contain different numbers of OT Books, yet all these Bibles close with the same verses: Rev. 22:18ff. Both cannot be right. Finally the Book of Deuteronomy contains similar verses (4:2 & 12:32). Does this imply that the Books after Deuteronomy are not inspired by God? No.
A third problem with the "Bible Alone" teaching is proper understanding of critical Bible passages. Most Protestant Christians promote personal interpretation of the Bible, i.e. anyone can interpret these passages by himself. Unfortunately this leads to chaos. For example over Baptism, some Protestants accept the validity of infant Baptism, while others do not. Some believe in the necessity of Baptism for salvation, citing Mark 16:16, while others disagree by citing John 3:16. They all claim to be Bible-based, but still they disagree over fundamental issues regarding salvation. Sadly the "Yellow Pages" phone directory is a witness to the many "Bible-Based" churches who disagree with each other over key issues of the Christian faith. Personal interpretation of the Bible naturally leads to a mire of human doctrines as a result of differing personal opinions.
The Bible was not written as a catechism. It is a collection of many different styles of writing - poetry, history, parables, letters, songs, etc. - requiring different ways of understanding. Sometimes Jesus in the Gospel purposely taught in figurative language and parables, which makes literal interpretation impossible. Even St. Peter admits that St. Paul's Epistles can be difficult to understand:
...Paul wrote to you according to the wisdom given him, speaking of this as he does in all his letters. There are some things in them hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures. [2 Peter 3:15-16]
Finally the Ethiopian eunuch in Acts 8:30ff needed St. Philip to explain the Book of Isaiah. Obviously not everyone can understand the meaning of Scripture by simply reading it. More is required. These difficulties in the Bible demand an independent visible teaching authority that is guided by the Holy Spirit.
Even the Bible points to the importance of the Church for teaching the Truth. According to St. Peter in the Bible:
First of all you must understand this, that no prophesy of Scripture is a matter of one's own interpretation, because no prophecy ever came by the impulse of man, but men moved by the Holy Spirit spoke from God. [2 Peter 1:20-21]
At least prophecies in the Bible are not a matter of personal interpretation. These prophesies must be properly interpreted by "men moved by the Holy Spirit" since the Holy Spirit is the Author. These "men" are the Bishops of the Church - the successors to the Apostles (Acts 20:28-32). Finally the Bible does not call itself the bulwark of the truth; however, St. Paul does make reference to the Church in those terms:
...the household of God, which is the Church of the living God, the pillar and bulwark of the truth. [1 Tim. 3:15]
According to the Bible, the Church is "the pillar and bulwark of the truth."
All Christians, including Catholics, should read the Bible in order to grow more in the faith; however, we still need the Church. The Church is needed to accurately pass on Apostolic Tradition (Romans 10:17), define the canon of the Bible (i.e. list the inspired Books), safeguard the accurate transmission (e.g. translations) of the Bible and interpret key passages, all with guidance from the Holy Spirit according to God's Will. The Church is needed for other reasons too. It must be understood that the Church is not merely men making arbitrary decisions but men executing authority from God guided by the Holy Spirit. The Church may at times be tested by scandals or scarred by the sins of men. We may sometimes disagree with the policies of the Church, but she is still the instrument of the Holy Spirit. This visible Church is the one built by Jesus Christ on St. Peter, the rock (Matt. 16:18-19; John 1:24). This is the Catholic Church.