The Bible as you all know was formed about 350 years after Jesus. The Bible is a form of Sacred Tradition, for what is in it was originally taught orally.
Now Catholics believe Sacred Tradition is also the Word of God. In this discussion it is important to keep in mind what the Catholic Church means by tradition. *The term does not *refer to legends or mythological accounts, nor does it encompass transitory customs or practices which may change, as circumstances warrant, such as styles of priestly dress, particular forms of devotion to saints, or even liturgical rubrics. Sacred or apostolic tradition consists of the teachings that the apostles passed on orally through their preaching. To the successors of the apostles, sacred Tradition hands on in its full purity God’s word, which was entrusted to the apostles by Christ the Lord and the Holy Spirit. These teachings largely (perhaps entirely) overlap with those contained in Scripture, but the mode of their transmission is different.
They have been handed down and entrusted to the Churchs. It is necessary that Christians believe in and follow this tradition as well as the Bible (Luke 10:16). The truth of the faith has been given primarily to the leaders of the Church (Eph. 3:5), who, with Christ, form the foundation of the Church (Eph. 2:20). The Church has been guided by the Holy Spirit, who protects this teaching from corruption (John 14:25-26, 16:13).
Paul illustrated what tradition is: “For I delivered to you as of first importance what I also received, that Christ died for our sins in accordance with the scriptures. . . . Whether then it was I or they, so we preach and so you believed” (1 Cor. 15:3,11). The apostle praised those who followed Tradition: “I commend you because you remember me in everything and maintain the traditions even as I have delivered them to you” (1 Cor. 11:2).
The Christian faith existed and flourished for years before the first book of the New Testament was written. The books of the New Testament were composed decades after Christ ascended into heaven, and it took centuries for there to be general agreement among Christians as to which books comprised the New Testament.
For ALL Bible-Only Christians & Protestants:
Furthermore, the reason you accept the books(in the bible) you do is that they were in the Bible someone gave you when you first became a Christian. You accept them because they were handed on to you. This means you accept the canon of the New Testament that you do because of tradition, because tradition is simply what is handed on to us from those who were in the faith before us. So your knowledge of the exact books that belong in the Bible, such as Philemon and 3 John, rests on tradition rather than on Scripture itself!