Many Evangelical and Fundamentalist Christians hold that the Bible is the literal, truthful, reliable, accurate, and authoritative word of God. The view arose out of -- but is not identical to -- the concept of sola scriptura ("scripture alone"), which was a rallying cry for Protestants during the Reformation.

Internal evidence

The most naive belief in biblical inerrancy, and the one that is most often encountered on Sunday morning television and in the pamphlets that street preachers hand out on city corners, is that the Bible is inerrant simply because it says it is. When asked why she believes the Bible is inerrant, this sort of Christian will usually point to 2 Timothy 3:16, which reads:

All scripture is inspired by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work. (RSV)

Other Biblical passages are occasionally added to 2 Timothy 3:16 as "proofs" of inerrancy. These include:

• Matthew 5:18, in which Jesus asserts that not a single letter, not even a stroke (the equivalent of the dot on an i), will pass from the Law until all is accomplished.
• 2 Peter 1:20-21, which says that "no prophecy of scripture is a matter of one's own interpretation," but rather, that it is the work of the Holy Spirit speaking through human beings.
• Revelation 22:18-19, which declares that horrible punishments will be meted out to anyone who alters "this book."
• various passages in the Hebrew Bible, particularly in the Psalms, which describe the word of God as being eternal and true.
• a number of stories about God speaking through church leaders in the presence of their opponents.

Obviously it is fallacious to take a text at its word about its own truthfulness -- plenty of works of fiction or satire insist that they are describing historical events, and all but the most gullible readers know better. Even scripture itself warns the reader to be discerning when it comes to religious claims. According to Matthew 24:23-25, false Christs will try to mislead good people with fake prophecies and, presumably, fake scriptures. Therefore faithful Christians themselves are expected not to believe every "scripture" they encounter, which is why evangelical Christians will not hesitate to condemn, say, the Qur'an or the Book of Mormon.

External evidence

A slightly more thoughtful defense of inerrancy -- though still not one that would convince an atheist or a member of a non-Christian religion -- is that the Bible is inerrant because nothing God says could be any other way. Christians who use this defense of inerrancy come to the belief in God through other avenues (witnessing a miracle, finding comfort in a church, being persuaded by Christian philosophy, believing that a prophecy has come true, or what have you) then conclude that the Bible is witness to that truth which was discovered through other means.

Inerrancy and Inspiration

The Greek word that is usually translated "inspired" means "breathed by God," and different Christian denominations disagree on just what exactly that means. The most rigid view of inspiration says that all the words of scripture are God's own, and that the human authors of the Biblical texts transcribed them directly. (This is similar to the Muslim view of the role of Muhammad in the transmission of the Qur'an.)

Christians of a more liberal stripe tend to believe that God inspired human writers by means of inner experiences and knowledge, which those writers then put into writing in their own words. This gives a bit more "wiggle room" for interpretation, since this view posits a human element in the development of scripture. Where a hardcore inerrantist would say that not only is everything in the Bible true, but it is also clear, a liberal Christian might say that the Bible is true but in need of careful interpretation and historical analysis.

Arguments Against Biblical Inerrancy

• Contradictions.
  Skeptics love hunting down passages in which the Bible contradicts itself. Was Jesus born in a house or a stable? How many pairs of animals were on Noah's Ark? Was there one Gerasene demoniac or two? Were women created before plants or afterward? Just what exactly were Jesus' last words? Were the Amalekites destroyed by Saul, by David, or by the Simeonites? Did Judas hang himself or did he explode? Did Jesus refuse to give signs to his generation or were signs all he gave them? And so on, and so on, and so on, ad nauseam.
  The responses to this accusation vary. Fundamentalists tend to claim that what people think of as contradictions are not contradictions at all. Many have spent immense amounts of time and effort writing elaborate timelines and family trees in order to explain how it all matches up. Christians of a more mystical bent, following Origen, explain that apparent contradictions are really paradoxical expressions of truths too deep for the human mind to comprehend. The most liberal answer is that difficult passages are metaphors, or that they are a product of a human mind rather than God's eternal truth. However, people who resort to this last explanation are rarely called inerrantists.
• Offensive passages.
  Biblical law makes various judgements about controversial issues such as homosexuality, as everyone knows. However, and more troublingly, it seems to say weird things about commonsense topics as well. It spends a lot of time talking about slavery without ever suggesting that it is bad; it condones the treatment of women as objects; it labels a lot of apparently trivial crimes as punishable by death; it seems to take polygamy and concubinage for granted; and it proposes a rather belligerent foreign policy that includes genocide. Many people think that such a document could not possibly represent a divine morality.
  Again, Christian responses to this accusation are mixed. Some Christians are perfectly willing to accept "Biblical" teachings on slavery, women, and war, and look forward to living in a world where those views have government sanction. Others explain that the Jewish law was superseded by Jesus' teachings; this neatly does away with some of the more embarrassing stuff in Leviticus, though it does not address some awkward moments in the New Testament (Jesus cursing a fig tree for not producing fruit out of season leaps immediately to mind). Still others say that the human authors of the Bible did the best they could given their own social upbringing, and that we have to take their historical context into account -- but again, these kinds of Christians probably shouldn't be called inerrantist even if they believe the Bible is "true" in some sense.
• Conflicts with science.
  "Jesus said that the mustard seed is the smallest of all seeds! There's lots of seeds smaller than that one! Obviously he was totally ignorant about biology and couldn't possibly have been God!" Complaints about the un-scientific nature of the Bible range from disbelief in miracles to skepticism about Biblical cosmology. Frankly, I'm bored out of my wits by arguments about how much rain it would take to cover the tops of the mountains or whatnot. These days, both sides of the evolution vs. creationism debate strike me as very shrill and lacking in subtlety. I invite you to look at other nodes on the topic if it interests you.
• Internal evidence.
  The Bible does indeed insist upon its own truth in places, but there are points in the Bible which suggest that its authors were ordinary humans like anyone else. For instance, in 1 Corinthians 1:14-16, Paul asserts that he only baptized two people, then corrects himself and adds a third name to the list. After that, he says that he can't remember who else he might have baptized. Such a slip of the memory might appear in any piece of correspondence, and I certainly don't hold this one against Paul. However, it complicates the idea that Paul was acting as God's infallible mouthpiece whenever he wrote anything down.

Scriptural Inerrancy in Other Religions

Fundamentalist and evangelical Christian views of Biblical inerrancy do have some things in common with traditional views of scripture in Islam and Judaism, but there are some important differences.

For instance, Islam is so firmly committed to the idea of the Qur'an as God's word that it does not consider translations of the book into other languages to be authoritative. For this reason, Muslim children are taught the Qur'an in Arabic no matter where in the world they live, and Arabic is the language in which the Qur'an is recited in mosques. Even the most radical Christian inerrantists, by contrast, are not especially wedded to Hebrew, Aramaic, or Greek, and in fact there are significant denominations of Christians who believe that English or Latin translations of the Bible are superior to the Greek originals. (The argument in support of these views are rather convoluted, but they are more common than you might think; see Jack Chick's web site for a typical example of "KJVO" Christianity.) Translation has always been a vital part of the Bible's history, and today's Christians tend to think that the "meaning" of scripture is not dependent on its original language.

Perhaps for this reason, Christianity has never developed a tradition like the Jewish Kabbalah (though some Christians did appropriate Kabbalah for their own purposes in the Renaissance). Jewish mystics would count and rearrange the Hebrew letters of the Torah in search of deep truths. Even the Talmud, which is hardly a mystical text, spends a lot of time comparing synonyms in the interest of deciding why God chose to use one rather than another. This attitude simply never took hold in Christianity, which seems to have a very different understanding of "meaning" than its sister religions.

Further Reading:

A good source of information on differing views of Biblical inerrancy, along with a bibliography, can be found on the Religious Tolerance web site:
http://www.religioustolerance.org/inerrant.htm