For my write-up today on volume 4 of John Meier's A Marginal Jew: Rethinking the Historical Jesus, I'll use as my starting-point Meier's discussion of Matthew 19:9, which (in the King James Version) states: "And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery."
Meier's position appears to be that the "except for fornication" clause was added due to "some particular problem within Matthew's church", either by Matthew himself or by the M tradition (pages 104-105). A reason for this conclusion is that Paul, Mark, and Luke do not mention this exception clause, and they seem to treat Jesus' command as an absolute ban on divorce and remarriage (Mark 10:11-12; Luke 16:18; I Corinthians 7:10-11). Paul, however, as Meier notes, "creates an exception for a special case on his own authority" (page 105): Paul allows a marriage to be dissolved if the non-believing spouse chooses to divorce.
Does this undercut the Bible's authority as the word of God? I can understand how people can think that. I remember hearing an evangelical biblical scholar say that he needs to hear the little old ladies at his church dogmatically appeal to Scripture as "the word of God". I didn't hear everything that he said, but I can think of a reason that he would feel that way: When he's reading books and articles that treat the Bible as a collection of human documents, then it's easy to get away from believing that the Bible is the word of God. After all, if Jesus said one thing, and some guy comes along and adds a clause that changes the meaning of what Jesus originally said, then how can we believe that all of the Bible reflects an unchanging will of God? It looks like a book that contains different human opinions. In a class, I was one time saying that the Bible was the word of God, and my professor responded, "What you call God, I call a redactor!"
There are a lot of people who feel liberated by the historical-critical method, precisely because it presents the Bible as the words of a variety of human beings, none of whom was infallible. Whereas my friend liked the little old ladies at his church dogmatically telling him that the Bible is God's word, since he felt that this kept him on the straight-and-narrow, others would like to get away from that dogmatism altogether. They've been abused by people who appeal to Scripture to justify their abuse, or they believe that some of the Bible's rules result in unhappiness. And then there are those who try to hold on to the Bible as Scripture, but they just can't. They believe that the Bible obviously reflects the opinions of fallible human beings, some of whom held ideas that are unjust (i.e., slavery, sexism, etc.), and they're tired of making excuses for the Bible, or doing mental gymnastics in an attempt to argue that the Bible indeed is perfect.
And then there are those who actually believe that the Bible can function as a valuable source for religious practitioners. They do not see the Bible in a fundamentalist sense, however, but they maintain that the flux and adaptation that are within the Bible are models for how the church should interact with the book. After all, if Matthew could add an exception clause to Jesus' teaching in an attempt to meet a pastoral need within his church, then why should we treat what is in the Bible as an absolute and rigid standard for how we should live our lives? Perhaps we can adapt the tradition, or change it in light of our current situation. What I'd ask, though, is if our changes can get to the point where we're not faithful to the tradition, period.