In advocating for a strong military response to the Islamic State (IS) in Iraq and Syria, Tony Blair has also outlined the need for a broader approach to tackle Islamism in the world today.

In a lengthy essay published on his Faith Foundation's website entitled 'The Way Ahead', the former prime minister says: "It is clear that there is a fundamental problem with radical Islamism".

"Islamism of course is not the same as Islam," he explains. "The religion of Islam is an Abrahamic religion of compassion and mercy. For centuries it shamed Christendom with its advances in science and social development.

"This is not a clash of civilisations," he continues. "It is a struggle between those who believe in peaceful co-existence for people of all faiths and none; and extremists who would use religion wrongly as a source of violence and conflict. Our enemies are those who would pervert Islam. Our allies are the many Muslims the world over who are the principal victims of such a perversion."

Blair says we need to "join the dots" between many of the major conflicts in the world, recognising that a significant number of them are related to some form of Islamism.

"I say that what is happening in Syria, Iraq, and across the Middle East; and what is happening in Pakistan, Nigeria, Mali, or in parts of Russia or in the Xinjiang province of China or in multiple other parts of the globe, are linked.

"They form different parts of one struggle. They all have their individual aspects. [...] But they have one huge and central element in common: extremism based on an interpretation of Islam which represents a clear ideology that, even if loosely at times, is shared by all these different groups of extremists."

We are in danger, he says, of treating militant Islamism as a "fringe" view, or "a sort of weird cult confined to a few fanatics." But this will prevent us from tackling the threat effectively, he argues.

"The problem is that we're facing a spectrum of opinion based on a world view which stretches far further into parts of Muslim society. At the furthest end is the fringe. But at the other end are those who may completely oppose some of the things the fringe does and who would never themselves dream of committing acts of violence, but who unfortunately share certain elements of the fanatic's world view."

Elements he identifies as part of this view include support for replacing secular governance with Islamic law, and a view of the West that is "innately hostile".

Islamism in this sense, Blair says, is an ideology preached to "tens of millions" of Muslims around the world.

"It is the spectrum that helps create the fringe," Blair argues. "A large part of Western policy – and something I remember so well fighting in Government – is based on the belief that we can compromise with the spectrum in the hope of marginalising the fringe. This is a fateful error. All we do is to legitimise the spectrum, which then gives ideological oxygen to the fringe."

Blair argues that militant groups grow when they are no longer resisted. For this reason, he says that the West should not rule out the idea of troops on the ground.

"We have to fight groups like ISIS," he says. "There can be an abundance of diplomacy, all necessary relief of humanitarian suffering, every conceivable statement of condemnation which we can muster, but unless they're accompanied by physical combat, we will mitigate the problem but not overcome it."

However, he does recognise that the broader spectrum of Islamist ideology should not be dealt with in the same way as the fringe (those who endorse militant Islamism). This, Blair says, should be tackled by exposing and opposing Islamist views, as well as engaging those who hold them in debate.

And while Blair says that non-violent Islamists should not be oppressed, he does also argue that we should respond to their views with conviction.

"Certainly in our types of society, people are perfectly entitled to hold views that we believe are destructive to our way of life and that we profoundly disagree with. Provided that that they express them within the law, that is their right.

"But it is also our right to point out why they are indeed incompatible with all we hold dear. And it is our duty, if we believe in what we say we do, to take on the argument with vigour and to watch with vigilance to see that Islamism does play by the rules in our own country."