Johann Hari

So the jihadists who pine for 7/7 24/7 are back, trying to make a Brown week into a black one. It is only luck that their incompetence turned their attempts at mass murder in London and Glasgow into a scene from Carry on Up the Jihad, where one of their car bombs was towed away and their merry tossing of Molotov cocktails succeeded only in incinerating themselves.

But as we sit anxiously on the highest security alert, the old question is back. Why? Why would young British men (and they will probably turn out to be British) want to randomly murder as many of their fellow citizens as possible in nightclubs and airports? The French intellectual Regis Debray once called car-bombs "manifestos written in the blood of others." What does this manifesto say?

I have interviewed jihadis and wannabe-suicide-murderers from London to Gaza, from Abu Hamza's hooks to the teenagers he inspired. Their motives are a black gloop of contradictions, but let's look at the two over-arching - and conflicting - explanations that have been most frequently served up for home-grown jihad, because both contain some truths.

We can call the first the Blowback Thesis. In the early 1950s, the CIA invented this term to describe the unintended consequences that would hit the United States for interfering in other countries. Its application here is obvious: turn Iraq into a killing field, and some Muslims back in Britain will be so enraged that they will - to use the old phrase coined by violent anti-Vietnam protestors - "bring the war home".

The exponents of this view have some impressive evidence on their side. In the videos they left behind, the 7/7 bombers named the British government's invasion of Iraq and support for Israel as their primary motives. Britain's own Joint Intelligence Committee had warned before the war that "the threat [from al Quaeda] would he heightened by military action against Iraq".

But the blowback thesis also contains holes. It can make the jihadis sound far more humanitarian than they actually are. One expert declared this weekend on the BBC World Service that these bombers are "outraged by the killing of civilians in Afghanistan" - but actually, these Islamists vehemently support the killing of Afghan civilians, as long as it's done by Jihadis Like Us. When the Taliban were butchering civilians in Afghanistan for the "crimes" of adultery, homosexuality or simply being female and showing your face in public, they held them up as a model for the world. Abu Hamza told me it was "the perfect society".

A bigger problem still with this thesis is that jihadist bombs have been recently planted on trains in Germany (thankfully defused). In Canada a plot was just rumbled to behead the Prime Minister. Both countries vehently opposed the war in Iraq and offer vast sums in aid to the Palestinians.

So blowback is a necessary but not sufficient explanation for these bombings. What fills the holes in this case? We can call the second explanation the Totalitarianism Thesis. This argues that jihadism is not simply a mirror-image of what our governments do to Muslims: it has its own vision of a renewed Islamic Caliphate under sharia law that it wishes to impose on the Middle East and eventually the world. In the absence of achieving this impossible goal, jihadis will voraciously seek out grievances based on the failure of the world around them to conform to their Puritanical desert morality.

Is this true? A few hours before the first carbomb was discovered, a contributor to the chatroom on the Islamist al Hesbah website wrote: "Today I say: Rejoice, by Allah, London shall be bombed." He gave his reasons for the murder plot he was clearly involved in: the Iraq war, and - just as important - the honouring of perhaps our greatest novelist, Salman Rushdie. The choice of target - a club on Ladie's Night - is also revealing. When a similar gang plotted to blow up the Ministry of Sound in 2004, they talked about their desire to burn alive the "slags dancing around."

This is a reminder the bombers are not only reacting against the worst in our system of government: the torture and the use of chemical weapons in Iraq, Guantanamo Bay, support for Arab dictators. They oppose the best in our system of government too: the intellectual freedom to write novels that question religion, the sexual freedom of women to pick their own partners. When I receive my own tedious drizzle of jihadi death-threats, they always mention my homosexuality long before they get to my views on foreign policy. In his "Address to the American People" in October 2002, Osama Bin Laden said "the worst kind of event" committed by America was not a foreign policy atrocity - of which there are many - but "your President Clinton's immoral acts committed in the official Oval Office" with Monica Lewinsky. To them, this is a war against blowjobs and novellists as much as a war against occupation.

So what can we do to defuse the ticking bomb of British jihadism? On all fronts, the solution lies not in abandoning the values of liberal democracy, but in adhering to them much more scrupulously. If we restrain our leaders whenever they try to violate our values by using torture, or chemical weapons, or arming tyrants - indeed, if we put them on trial for it - we will choke off the more obvious blowback. But that's not enough. We also need to unpick the totalitarian ideology of jihadism by democratically opening up Islamic theology, so that over a generation, fewer and fewer young men can convince themselves they are "good Muslims" when they murder innocents.

At the moment, there is an epic battle within Islam between jihadi literalists and those Muslims (disproportionately women) who want to reinterpret the Koran to make it compatible with modernity, but today this is a horrifyingly lop-sided fight. The literalists are lavished with cash from the Saudi Arabian monarchy: their mosques are flooded with petrodollars, their imams are trained in Mecca, they receive piles of poisonous textbooks, and they are even given British government cash to run their own schools. The liberals, by contrast, scrape by with almost no funds at all.

We need to reverse this situation by banning the Saudi money designed to fundamentalize British Islam, and instead lavish government cash on the brave Muslim women's groups sprouting across the country. Free, independent Muslim women will raise their children with liberal readings of the Koran incompatible with blowing up "slags" or novelists. The French government has just begun to do this, with Nicholas Sarkozy appointing the heroic Muslim feminist Fadela Amara to devise his strategy for the Banlieues. But our government is failing to stop the Saudi poison because we are addicted to the oil they pump our way. As in Iraq, it seems that securing petroleum trumps undermining fundamentalism every time.

Until we complete this slow work of whittling down blowback and opening up Islam, we could face a carpark full of car-bombs - and we may not be so lucky next time.

You can send comments on this article to johann -at- johannhari.com or for publication in the Indie to letters -at- independent.co.uk

You can read my article about how 7/7 showed three faces of British Islam here, and my articles written immediately after the massacres talking about the long-term ways to undermine jihadism here and here.