François Hollande’s declaration of war against Isis (also known as Islamic State) was, perhaps, a natural reaction to the carnage in Paris but the situation is now so grave that we cannot merely react; we also need sustained, informed and objective reflection. The French president has unwittingly played into the hands of Isis leaders, who have long claimed to be at war with the West and can now present themselves as noble ­resistance fighters. Instead of bombing Isis targets and, in the process, killing hapless civilians, western forces could more profitably strengthen the Turkish borders with Syria, since Turkey has become by far the most important strategic base of Isis jihadis.

We cannot afford to allow our grief and outrage to segue into self-righteousness. This is not just the “Middle East problem”; it is our problem, too. Our colonial arrangements, the inherent instability of the states we created and our support of authoritarian leaders have all contributed to the terrifying disintegration of social order in the region today. Many of the western leaders (including our own Prime Minister) who marched for liberté in Paris after the Charlie Hebdo massacre were heads of countries that, for decades, have backed regimes in Muslim-majority countries that denied their subjects any freedom of expression – often with disastrous results.

One of these regimes is Saudi Arabia. Despite its dismal human rights record, the kingdom has been central to western foreign policy in the Middle East since the 1970s and western governments have therefore tacitly condoned its “Wahhabisation” of the Muslim world. Wahhabism originated in the Arabian peninsula during the 18th century as an attempt to return to the pristine Islam of the Prophet Muhammad. Hence, Wahhabis came to denounce all later developments – such as Sufism and Shia Islam – as heretical innovations.

Yet this represented a radical departure from the Quran, which insists emphatically that there must be “no coercion in matters of faith” (2:256) and that religious pluralism is God’s will (5:48). After the Iranian Revolution, the Saudis used their immense wealth to counter the power of Shia Islam by funding the building of mosques with Wahhabi preachers and establishing madrasas that provided free education to the poor. Thus, to the intense dismay of many in the Muslim world, an entire generation has grown up with this maverick form of Islam – in Europe and the US, as well as in Pakistan, Jordan and Malaysia.

In 2013, the European Union declared that Wahhabism was the main source of global terrorism. It is probably more accurate, however, to say that the narrowness of the Wahhabi vision is a fertile soil in which extremism can flourish. In the 19th and early 20th centuries, Wahhabi chieftains did indeed conduct violent military expeditions against the Shia but, during the 1930s, the Saudi kingdom abandoned military jihad and Wahhabism became a religiously conservative movement. Today, some members of the Saudi ruling class support Isis but the Grand Mufti has condemned it in the strongest terms. Like Osama Bin Laden, Isis leaders aim to overthrow the Saudi regime and see their movement as a rebellion against modern Wahhabism.

Military action in Syria will not extirpate Islamist extremism elsewhere. In order to be fully successful, President Hollande’s campaign must also include a review of domestic policy. France has signally failed to integrate its Muslim population. Most of the terrorists responsible for the atrocities of 13 November appear to have been disaffected French nationals. So, too, were the Kouachi brothers, who committed the Charlie Hebdo massacre, and Amedy Coulibaly, who hijacked the Jewish supermarket in January. All three lived in notoriously deprived suburbs of Paris and – evoking France’s colonial past – were of Algerian and Malian descent. Psychiatrists who have investigated people involved in the 9/11 plot and in subsequent attacks have found that these terrorists were not chiefly motivated by religion. Far more pressing has been the desire to escape a ­stifling sense of insignificance. Powerless at home, many of them alienated by the host culture, young Muslim men in the West are attracted by the strong masculine figure of the jihadi and the prospect of living in a like-minded community, convinced that a heroic death will give their lives meaning.

As they debate the feasibility of British air strikes in Syria, some MPs have insisted that they must be accompanied by negotiation and diplomacy. Again, these cannot be conducted in a spirit of superior righteousness. There must be a recognition that the West is not the only victim of Muslim extremism. We seem curiously blind to this. Far more Muslims than non-Muslims have been killed by Isis, yet this is rarely mentioned. Two weeks before the Charlie Hebdo atrocities in January, the Taliban murdered 145 Pakistanis, most of them children; two days after it, Boko Haram slaughtered as many as 2,000 villagers in Nigeria. Yet, compared with the Paris attack, the media coverage in the West was perfunctory. There has been little acknowledgment that the refugees whom many would seek to exclude from Europe have experienced the horrors we saw in Paris on a regular basis in Syria or Iraq. Already we seem to have forgotten that more than 40 people in Beirut were killed by two Isis suicide bombers on 12 November.

This heedlessness – a form, perhaps, of denial – does not go unnoticed in the Muslim world. The Iraq War showed that a military campaign cannot succeed if it fails to respect the sensibilities of the local people. Western governments must understand that their ­nations bear considerable responsibility for the present crisis – Isis is, after all, the product of the ill-considered Iraq War. And, as long as we mourn only our own dead, we cannot escape the accusation – frequently heard in the developing world – that the West has created a global hierarchy in which some lives are more valuable than others.

Karen Armstrong is the author of “Fields of Blood: Religion and the History of Violence” (Vintage)