There are many ideas that float around in our culture today about the reliability or accuracy of the Bible. Detractors often point out that since self-proclaimed “Christians” disagree about the meaning of so many different passages, the Bible must be either unknowable or unclear.
If you’re interested in this subject, I would highly recommend a short book recently published by Kevin DeYoung called Taking God at His Word. It is a very readable and engaging (and concise!) look at the doctrine of Scripture.
In chapter 5, DeYoung talks about the authority of Scripture, and particularly addresses the reason large sections of the church tend to disagree on certain subjects. He believes (and I agree with him on this) that many of the issues in biblical interpretation have to do with what different branches of the church (or people for that matter) believe about biblical authority. The operative question: Does Scripture have the final word on matters of truth? Here are the answers given by 3 different branches of Western Christianity (in their own words):
1) Roman Catholic
The Church gives us her Tradition like a mother giving a child hand-me-down clothing that has already been worn by many older brothers and sisters. But unlike any earthly clothing, this clothing is indestructible because it is not made of wool or cotton but truth. It was invented by God, not man. Sacred Tradition (capital “T”) must be distinguished from all human traditions (small “t”).
Sacred Tradition is part of “the deposit of faith”, which also includes Sacred Scripture. It is comprised of the Church’s data, given to her by her Lord.
2) Liberal Protestant
The essential idea of liberal theology is that all claims to truth, in theology as in other disciplines, must be made on the basis of reason and experience, not by appeal to external authority. Christian scripture may be recognized as spiritually authoritative within Christian experience, but its word does not settle or establish truth claims about matters of fact.
The supreme judge by which all controversies of religion are to be determined, and all decrees of councils, opinions of ancient writers, doctrines of men, and private spirits, are to be examined and in whose sentence we are to rest, can be no other but the Holy Spirit speaking in the Scripture.
Do you see the difference? For the Roman Catholic, “Tradition” and Scripture are equal authorities. For the liberal Protestant, “reason and experience” are the final authorities. For the Evangelical, Scripture alone has the final word. From the outside, it appears that there are different brands of Christianity, but it really all comes back to where we place the final authority. This is why you can walk into a “Christian church” that preaches the Bible every week and determines all matters of faith and practice therein, and walk into another “Christian church” a block away that has a practicing homosexual on the Deacon board. The difference? The final authority.
 Peter Kreeft, Catholic Christianity, quoted by DeYoung on page 76-77.
 Gary Dorrien, The Making of American Liberal Theology quoted by DeYoung on page 77.
 Westminster Confession of Faith, 1.10. quotes on page 77.