The Earth may not have stood still on 9/11, (the headline over the story in one newspaper), but the terrible events of that day dramatically altered the way we look at the world today, at global affairs, and at religion in particular.

Since the 9/11 attacks on the US homeland, the world has become acutely aware of what the novelist JG Ballard has called “the sinister fusion of religion and politics”.

History is replete with examples of the “sinister fusion” of which Ballard speaks. One need only mention the Crusades, the Inquisition, or the Thirty Years’ War.

It is also true, of course, that history provides us with manifold examples of a fusion of religion and politics that, far from being sinister, had a positive, beneficial, and enriching effect. But last month, we saw dramatic and traumatic proof of the toxic dimension of that fusion and its potency when Islamic extremists, the Taliban, regained control of the Afghan capital Kabul on August 15, after a 21-year war that was launched as a direct US response to the 9/11 attacks.

These events are a stark reminder — once again — that, in the words of Francis Fukuyama (author of The End of History), we need to understand “both the reasons behind religion’s surprising comeback and how it will shape the future of global politics”.

In her preface to the second edition (2009) of Religions in the Modern World, Linda Woodhead, Professor of sociology of religion at Lancaster University, summed up the changed appreciation of religion: “When the first edition was sent to the publishers in early 2001, the subject of religion in the modern world was still considered marginal by many people. In the intervening years, that situation has changed out of all recognition. Like it or loathe it, religion is back on the agenda again.

“As the first edition showed, religion was a major force in the modern world well before 2001. Contrary to claims about recent religious resurgence, religion has not popped up like some Jack-in-the-box. Rather, it has made itself known in ways which are harder to ignore. 

"The attack on the World Trade Centre on September 11, 2001, is the most obvious example, but other more incremental developments have also been important. 

These include global migrations which have brought religious pluralism to the heart of a supposedly secular Europe, the continuing growth of new forms of spirituality, and the reconfiguration of religion in a media culture.

“What has changed the most is thus the way we look at religion, and how seriously we take it. Religion is no longer dismissed as a private pastime, but is taken more seriously as a public and political force. 

"This change, in turn, impacts upon religion itself, often lending it new confidence and vitality, and increasing its range and power.” 

Religion has now entered the global age, and breaks down frontiers (which is one reason why the fall of Kabul can have international repercussions). 

And it is now seen in many quarters — not least in policymaking circles in the world’s major capitals — in a new light. 

More than ever before, religion is politically important today, and aspects of globalisation have undoubtedly contributed to this. 

“From the local to the global level, religion is — more than ever — an important and hotly debated part of modern life in the 21st century,” according to Malory Nye, author of Religion: The Basics.

What 9/11 also did was reopen — with a new urgency — the old debate about religion and violence. This is a debate with a long pedigree; we need only think of the Crusades in the 11th and 12th centuries, and the “wars of religion” that raged in the 16th and 17th centuries in the aftermath of the Reformation. 

This is also a debate that has a particular pertinence to the Irish situation, as former BBC journalist Martin Dillon has graphically reminded us in his book God and the Gun: The Church and Irish Terrorism, dealing with the Troubles in Northern Ireland, troubles which lasted from 1968 and the Good Friday Agreement of 1998, causing more than 3,600 deaths.

Mark Juergensmeyer of the University of California, in a preface to the paperback edition of Terror in the Mind of God: The Global Rise of Religious Violence, highlighted the central issue: “Perhaps the first question that came to mind when television around the world displayed the extraordinary aerial assaults on the World Trade Centre and the Pentagon on September 11, 2001, was why anyone would do such a thing.

"When it became clear that the perpetrators’ motivations were couched in religious terms, the shock turned to anger. How could religion be related to such vicious acts?” 

At first glance, any link between religion and violence seems incongruous. Yet since the 9/11 attacks, the world has become acutely aware that the fusion of religion and politics can indeed have sinister consequences. 

This conviction has been reinforced by the victory of the Taliban with their brand of radical Islam in Afghanistan.

For those of us accustomed to believe that religion is a force for good and a promoter of peace, and politics a means of creating a just and equal society, proof of the toxic and even lethal mix of the two has come as something of a shock.

This may be due to complacency, indifference or even ignorance on our part. 

Did too many of us in the West accept that religion was somehow “neutral” when it came to politics, or that religion even occupied a separate sphere — and that the twain ne’er shall meet? 

Why would we ever think that religion might be “political” or that politics would harness or exploit or subvert religion for its own ends?

It began, some would argue, after the Battle of the Milvian Bridge in 312AD, when the Emperor Constantine, emerging victorious after fighting under the sign of the Cross, bestowed great favours on Christianity, making it in effect the official (State) religion of the Roman Empire.

Attributing his victory to the Christian God, he forged a new alliance between altar and throne, between Church and State, marking the birth of political religion.

Its most modern — and extreme — manifestations are al-Qaeda and its offshoots and affiliates, Boko Haram, al-Shabab, and Islamic State, and also the Taliban, though this movement is rooted in another branch of militant Islam known as Deobandism. 

All the others are rooted in Wahhabism (named after its founder, Mohammed ibn Abd al-Wahhab), a fundamentalist, puritanical, and militant version of Islam that is the official or State religion of Saudi Arabia. The Deobandis, however, share many of the beliefs and ideologies of the Wahhabis.

The “politicisation” of religion is almost as old as religion itself. Some would go so far as to say that the politicisation of religion has been consubstantial with religion itself.

Rulers have always been cognisant of the importance of having religion on their side, not because of any innate regard for religion (at least not in all cases), but because of its utility value. Accordingly, over the centuries, they have plotted and schemed and pursued associations and alliances to gain the advantages and benefits that would accrue from winning over religion.

Emperors, kings, princes, sultans, despots, and tyrants have sought to harness, utilise, exploit, and yoke religion for their own purposes, to advance their causes, to legitimise their regimes, to sanction their policies, or to pacify the masses.

Democratically-elected leaders have also turned to religion with the aim of using it to bestow extra authority of the office of president or prime minister or taoiseach, and to bolster their programmes for government, or to underpin and divinely enhance their constitutions and charters of rights. 

Conversely, down the ages, religious leaders — popes, patriarchs, archbishops, rabbis, ayatollahs and evangelical preachers — have shown a readiness to form alliances and pacts with states, governments, leaders of political movements, and even dictatorships. 

The main aim of these arrangements is to enlist state aid and support for the protection and promotion of religious freedom and religious tolerance.

But these alliances were often entered into in the hope or with the intention that the State might confer privileged status on one particular religion above others, or in the expectation that the State might use its legislative apparatus to enforce a particular system of faith-based morality or even to favour a particular church by ensuring that its ministers of religion would be exempt from state taxes or would receive state stipends. 

All of this was perhaps best summed up by the Greek-born film director Costa-Gavras, who once said that if the Catholic Church has lasted for 2,000 years, this was because it has always been on the side of the powerful.

Of course, to some, the term “political religion” will seem an oxymoron, or a contradiction in terms. 

Politics may be defined as the art or science of government, the practice or study of forming, directing, and administering states or other political units, or, more narrowly, any activity concerned with the acquisition of power and gaining one’s own ends. 

Religion, on the other hand, is more difficult to define. The standard dictionary definitions specify belief in, worship of, or obedience to a supernatural being — God. 

But it is when religion is harnessed to a political cause, project, or objective which believers regard as being “divinely sanctioned” that the toxic consequences of which JG Ballard warned can occur.

As the Dalai Lama, the Buddhist leader, said during a surprise visit to the Glastonbury Festival in June 2015: “Human beings killing each other in the name of religious faith — unthinkable”. And yet the unthinkable is happening.

What is undoubtedly true — especially now in the aftermath of the triumph of the Taliban in Afghanistan, is this observation from Lyse Doucet, BBC chief international correspondent who covered the fall of Kabul: “If you don’t understand religion, including the abuse of religion, you don’t understand what is happening in our world”.