This is ironic, because the concept of scripture has become problematic in the modern period. The Scopes trial of 1925, when Christian fundamentalists in the United States tried to ban the teaching of evolution in the public schools, and the more recent affair of The Satanic Verses, both reveal deep-rooted anxiety about the nature of revelation and the integrity of sacred texts. People talk confidently about scripture, but it is not clear that even the most ardent religious practitioners really know what it is. Protestant fundamentalists, for example, claim that they read the Bible in the same way as the early Christians, but their belief that it is literally true in every detail is a recent innovation, formulated for the first time in the late 19th century.

Before the modern period, Jews, Christians and Muslims all relished highly allegorical interpretations of scripture. The word of God was infinite and could not be tied down to a single interpretation. Preoccupation with literal truth is a product of the scientific revolution, when reason got such spectacular results that mythology was no longer seen as a valid path to knowledge.

We tend now to read our scriptures for accurate information, so that the Bible, for example, becomes a holy encyclopaedia, in which the faithful look up facts about God. Many assume that if the scriptures are not historically and scientifically correct, they cannot be true at all.

But this was not how scripture was originally conceived. All the verses of the Quran, for example, are called ayat or parables; its images of paradise, hell and the last judgment are also ayat, pointers to transcendent realities that we can only glimpse through signs and symbols.

We distort our scriptures if we read them in an exclusively literal sense. There has recently been much discussion about the way Muslim terrorists interpret the Quran. Does the Quran really instruct Muslims to slay unbelievers wherever they find them? Does it promise the suicide bomber instant paradise and 70 virgins? If so, Islam is clearly prone to terrorism. These debates have often been confused by an inadequate understanding of the way scripture works.

People do not robotically obey every single edict of their sacred texts. If they did, the world would be full of Christians who love their enemies and turn the other cheek when attacked. There are political reasons why a tiny minority of Muslims are turning to terrorism, which have nothing to do with Islam. But because of the way people read their scriptures these strident, misplaced certainty. Reading gives people the impression that they have an immediate grasp of their scripture; they are not compelled by a teacher to appreciate its complexity. Without the aesthetic and ethical disciplines of ritual, they can approach a text in a purely cerebral fashion, missing the emotive and therapeutic aspects of its stories and instructions.

Solitary reading also enables people to read their scriptures too selectively, focusing on isolated texts and ignoring others that do not chime with their own predilections. Religious militants who read their scriptures in this way often distort the tradition they are trying to defend. Christian fundamentalists concentrate on the aggressive Book of Revelation and pay no attention to the Sermon on the Mount, while Muslim extremists rely on the more belligerent passages of the Quran and overlook its oft-repeated instructions to leave vengeance to God and make peace with the enemy.

Most of us have neither the talent nor the patience for the disciplines that characterised pre-modern interpretation. But we can counter the dangerous tendency to selective reading of sacred texts. The Quran insists that its teaching must be understood 'in full' (20114), an important principle that religious teachers must impart to the disaffected young.

Muslim extremists have given the jihad (which they interpret reductively as 'holy war') a centrality that it never had before and have thus redefined the meaning of Islam for many non-Muslims. But in this they are often unwittingly aided by the media, who also concentrate obsessively on the more aggressive verses of the Quran. We must all - the religious and the sceptics alike - become aware that there is more to scripture than meets the cursory eye.

Karen Armstrong is the author of The Battle For God A History Of Fundamentalism. The article appeared in The Guardian in Britain.