So the failed car bomb attacks on Glasgow Airport and London's West End have given Islam a bad name. No surprises there. According to new research published by Theos, the public theology think tank, more than seven in 10 people interviewed said that the planned attacks have damaged Islam's reputation.

The usual response to this kind of thing is to protest that Islam is a religion of peace. I want both to support and to challenge this conventional wisdom, and then to ask how justifiable the protestations of the other great monotheistic religions are.

I spent some years living in a multi-cultural area of Glasgow. Our next door neighbours, Mr and Mrs Rafiq, were the epitome of Muslim kindness and hospitality. There's not the slightest doubt that a huge majority of Muslims in this country regard the bomb attacks as utterly abhorrent.

They also regard them as an affront to Islam. But are they right to do so?

This leads us to the heart of the current problem. Islam is a religion of peace, with its emphasis on charity, justice and love for the neighbour. But to leave the matter at that is simply dishonest. Islam is also a religion of war. Both its history and some of its sacred texts tell us so. As well as many injunctions to peaceful living, there are some bellicose exhortations in the Koran and in the hadith (sacred commentary). The suicide pilots who flew innocent men, women and children to their deaths did so with the cry Allah Akbar - God is Good - on their lips, believing that they were fulfilling the revealed will of Allah.

Sacred scriptures are problems as well as resources. The reiteration of so-called infallible texts solves nothing. The warring sects of the Muslim world - what is happening today is as much evidence of a civil war within Islam as it is a clash of civilisations - all believe that the Qur'an is the final, literal word of God which cannot be challenged in any way. This is bad news for women, as well as for freedom of speech.

The sight of the baleful Ayman al Zawahri, deputy leader of al Qaeda, threatening an attack on Britain because novelist Salman Rushdie was honoured with a knighthood, is also bad news for Islam. What has been truly shameful is the response of those Brits who have said Britain should not have honoured Rushdie - one of the genuinely great writers of our time - because it might provoke wrath. The day we let terrorists determine the boundaries of our hard-won freedom of speech is the day that liberal democracy dies.

The Muslim world is being disfigured and dishonoured by unelected and unelectable religious zealots who will kill indiscriminately to impose their view of the world on unwilling others (including other Muslims). They must be resisted utterly, just as Nazism and Stalinism had to be resisted. Those on the British left who lend moral support to these Fascists are contemptible. One of the many tragedies of the grotesque Iraq adventure was that it took the eye off the terrorist ball and recruited many more terrorists; and the failure to broker a just Middle East solution has provided a disastrous pretext for chilling slaughter.

So am I saying that Islam needs a reformation, and that Christianity and Judaism are just fine? Absolutely not. Christianity is a religion of peace; it is also a religion of war. As with Islam, its sacred writings and its history - Crusades, Inquisitions and religious wars - bear this out. There has been a lot of God-endorsed smiting going on. More tea, vicar?

Ah, but that's all history, isn't it? Better say that in hushed tones in Belfast. Despite much squirming, Christianity and Judaism still do not disown their own toxic texts. Yahweh is presented - with an apologetic little cough, of course - as a genocidal tyrant who tells the tribes of Israel to slaughter everyone in their path (though virgins may be kept as prizes) on the way to conquest of the promised land. Milosevic was in the dock for less. There is a direct line between this ancient fanaticism and the problems in the Middle East in the Year of Our Lord, 2007.

I think of Dennis Potter's searing words: "Religion is the wound, not the bandage." Toxic religion's grievous bodily harm is life- threatening. Yet mainstream faith has life-enriching treasures to explore; the faithful of all three great monotheistic religions are, at their best, marked by generosity, compassion and justice.

The problem is that even within the mainstream there is an unwillingness to confront religion's badly-hidden grisly secret with courage and clarity. The confusion of humanly sacred texts with the very word of a mysterious and elusive God is now one of the greatest dangers of our time.