Tony Blair has reignited debate about the west's response to terrorism with a call on governments to recognise that religious extremism has become the biggest source of conflict around the world.

Referring to wars and violent confrontations from Syria to Nigeria and the Philippines, Blair, writing in the Observer, argues that "there is one thing self-evidently in common: the acts of terrorism are perpetrated by people motivated by an abuse of religion. It is a perversion of faith."

Identifying religious extremism as an ever more dangerous phenomenon, the spread of which is easier in an online age, he says: "The battles of this century are less likely to be the product of extreme political ideology, like those of the 20th century – but they could easily be fought around the questions of cultural or religious difference."

The former prime minister, who led the country into the Iraq conflict in 2003, appears to acknowledge that previous aspirations to export liberal democracy focused too much on political objectives.

But sources close to Blair insist that he is not in any way indulging in a mea culpa over past interventions by the west, including in Iraq. In the future, he writes, "the purpose should be to change the policy of governments; to start to treat this issue of religious extremism as an issue that is about religion as well as politics, to go to the roots of where a false view of religion is being promulgated and to make it a major item on the agenda of world leaders to combine effectively to combat it. This is a struggle that is only just beginning."

The promotion of religious tolerance, both within and between countries, states Blair, will be key to fostering peaceful outcomes around the world in the 21st century.

He uses his article to announce the creation a new online forum and database run by his Faith Foundation in collaboration with the Harvard Divinity School, which he hopes will become the world's leading source of information and debate about religion and conflict.

Blair argues that while the west needs to be ready to take security measures for its protection, such action alone, even military action, "will not deal with the root cause of extremism".

Debate over Blair's role in the invasion of Iraq will return to centre stage this summer when the long-awaited Chilcot report into the period running up to the war is published. It is expected to contain damning evidence of how President Bush and Blair jointly engaged in a rush to war to topple Saddam Hussein in the face of warnings of the risks of triggering sectarian divisions across the region.

In the article, Blair directly addresses the chaos left in the wake of the invasion when he argues: "All over the region and including in Iraq, where exactly the same sectarianism threatens the right of the people to a democratic future, such a campaign [for tolerance of other religious views] has to be actively engaged. It is one reason why the Middle East matters so much and why any attempt to disengage is so wrong and short-sighted."

Critics of the neoliberal interventions of the last decade – including those in Iraq and Afghanistan – have argued that they rely too much on a political "freedom" agenda, focusing on the toppling of tyrants in the belief that the introduction of democracy would be a panacea.

But some fear that to focus too much on deep-seated religious schisms is to ignore the local complexities of such regional conflicts.

On Saturday, Jonathan Eyal, the international director of the Royal United Services Institute, took issue with Blair's analysis and any implication that western governments were not informed before invading Iraq of the sectarian violence that was likely to be stirred up.

"Predicting when religious differences may descend into outright violence is never easy," he said. "But it's just fallacious to claim that those who ordered and led the 2003 Iraq war lacked access to the necessary information about the complexities of that country's ethnic and religious divisions, or could have ever assumed that they could complete their intervention without rekindling religious bloodshed."

He added: "It was not the lack of sufficient knowledge about history and religion which led to the Iraqi debacle, but the lack of restraint among politicians who had all the relevant information at their fingertips."