The word "fundamen-talism" is usually linked with "Islamic" in news headlines. Indeed, it is often associated with terrorist organisations and their threat to Western societies.
But it was a group of Christian Protestants who were first to be labelled fundamentalist. In the early 20th century, many American Protestants, feeling that their old values were being overwhelmed by a new intellectualism, published 12 books - The Fundamentals - setting out what they regarded as the non-negotiable basics of their faith. The books all derive from the premise that the Bible is literally true, word by word.
Today, followers of such beliefs avoid calling themselves fundamentalists because the term has become pejorative and because they do not accept that their views are marginal. The nearest to an acceptable self-labelling is the term "evangelical", which covers a wide highway of faith from, as it were, just off the centre line right out to the edge of the hard shoulder.
Even for many liberal religious believers, a particular stumbling block is the status of other faiths. Tolerance of other religions is one thing; any suggestion that they are all equally valid is something else. Some Christians, for example, quote from the Bible to claim that faith in Jesus is the only route to Heaven.
Fundamentalism displays many of the same characteristics across different religions. There is strict, uncritical reliance on a holy book, a belief that religious law should regulate secular affairs and an insistence that cultural practices that were defined long ago must be retained intact and defended against "modernists". (Hence the importance of dress codes, dietary rules and gender roles.) Some would say there's an extra ingredient - an inflexible insistence that these "fundamentals" must apply to everyone and that it is morally right to stifle disagreement.
Fundamentalism that justifies violence is better labelled as extremism.
Teachers will occasionally have pupils with extremist views, imported from home or the place of worship. More commonly they will find themselves dealing with the opposite side of the argument - a popular belief that all Muslims (or all Catholics, Protestants or Jews) are murderers or terrorists. The best defence is to understand where religious extremism comes from.
If you believe that the truth of your religion is God given and inviolate, and must determine how your community is run, then you also believe that non-believers threaten the social order. From there you may reach a position where you see nations run by non-believers as godless and threatening, and violence against these states as justifiable because you are defending your faith. So there is an extreme Islamic view, for example, which uses the concept of "jihad" ("striving or struggling in the way of God") to justify attacks on those who are believed to threaten Islam.
In world terms, though, this is a minority view. Most Muslims believe that jihad refers primarily to the personal struggle to keep the faith in the face of temptation and distraction, and secondly to the Muslim's duty to defend Islam - militarily if needs be - against direct attack. This does not, say most Muslims, justify terrorist actions. The Koran forbids the taking of innocent lives, even in war.
Most deeply religious people will find something in school life to upset them. Here are three common examples: l Muslims and pigs. Some Muslims worry about jolly anthropomorphic pig characters in literature and on TV, despite mainstream Islamic leaders saying there is nothing in Islamic law or writing to justify their concern.
* Christians and the occult. A belief in the literal existence of Satan leads, logically, to a fear of children becoming exposed to his influence. So evangelical Christians don't like Halloween, and may object to books about witches and wizards.
* Teaching of non-Christian religions. Many Christian parents worry about a multi-faith approach to religious education and at the way, for example, Ancient Egyptian belief is taught in history lessons. They find it difficult to distinguish between teaching the religion and teaching about the religion.
Sir Robert Dowling, head of George Dixon International School in Birmingham, deals with religious differences every day. Problems are rare, although sometimes politics intrude, as they did after September 11.
"Some of the Muslim boys and girls felt under siege," he says, "so in assembly I said that no kid in this school was to hold their head down because they were a Muslim. Then I told them a bit about the Christian Crusades, and what Catholics had done to the Incas in the name of the Pope.
They didn't half listen to that. It was fairly bloody stuff."
A practising Catholic, he demonstrates that you can have deeply held convictions and yet have respect for what others believe.
Assembly, he feels, is an important arena for demonstrating these values:
"You can tell stories and give messages that are common to all religions. I discuss similarities between holy books, and I'll quote from them."
At Ramadan, he talks to groups of Muslim pupils. "I tell them about Christ fasting in the desert for 40 days, and how we observed Lent when I was a boy. And I know that the father of one of my Muslim students said to his son 'You listen to him, he is a man of faith.' "
* Don't argue. Faith is not a matter for debate for a fundamentalist.
* Don't, by word or body language, seem to be dismissive or contemptuous of any sort of religious belief.
* Be honest about your own beliefs (or doubts). Only by doing so can you demonstrate your respect for people with different beliefs.
* Be positive. Tell stories that show people of faith being tolerant and compassionate.
* Arm yourself with knowledge. Learn about the religious beliefs of your pupils.
* Emphasise in letters and talks to parents the distinction between teaching religion and teaching about religion.
* Quote the holy books - not in argument, but to illustrate the stories and messages you give in class or assembly. Use the points at which holy books agree. The inspirational story of Moses - someone of humble birth who learned, through great adversity, the qualities necessary to lead a nation to freedom - is common to Judaism, Islam and Christianity. It is also important to look at shared values such as giving to the poor, giving and sharing food and protecting the weak.
* Be open with parents about the curriculum and be sensitive to what might cause problems. Don't change anything that you know must be done, but be ready with explanations.
* Realise that you can't change the world. There are some issues that you just have to fudge and work round, giving a little here, agreeing to disagree there.
The more open, accepting, welcoming and friendly your school regime, the more likely it is that your judgment and good faith will be trusted.