How are we to understand last week's events in Paris? Why are people prepared to kill and die for their beliefs? How should liberal democracies respond? Many people must be asking themselves these questions. A remarkable man, Eric Hoffer, addressed them in a book published in 1951: The True Believer: Thoughts on the Nature of Mass Movements. The ideas in his book, developed in response to Nazism and communism, echo powerfully today.

Hoffer was born at the turn of the 20th century and died in 1983. He worked in restaurants, as a migrant farmhand, as a gold prospector and, for 25 years, as a longshoreman in San Francisco. Self- taught, he could penetrate to the core of a topic in brilliant and limpid sentences. The True Believer is among my favourite books. It is once again an invaluable guide.

Who, then, is a true believer? Said and Cherif Kouachi and Amedy Coulibaly, the men responsible for last week's terrorist attacks in Paris, were true believers. So are those active in al-Qaeda, the Taliban, Islamic State or Boko Haram. So, once, were Nazis and committed communists.

True believers, argues Hoffer, are not characterised by the content of their faith, but by the nature of its claims. Their beliefs claim absolute certainty and demand absolute loyalty. True believers are those who accept those claims and welcome those demands. They are prepared to kill and to die for their cause, because its success in the world is more important to them than their lives or indeed anybody’s life. The true believer is therefore a fanatic.

The fanatic is a familiar character in history. Fanaticism is born of temperament, not ideas. The fanatical temperament can express itself in many different ways. Hoffer’s was an age of secular religions. Reality killed the religions that promised salvation on Earth. But it cannot kill religions that promise eternity. The latter are now, once again, the most powerful forms of belief, though nationalism may yet run them close.

With God on our side

Indeed, religion and nationalism have frequently reinforced one another: God, after all, is so often held to be on “our side”. Thus, Hoffer states that “in modern times nationalism is the most copious and durable source of mass enthusiasm and that nationalist fervour must be tapped if the drastic changes projected and initiated by revolutionary enthusiasm are to be consummated”.

One of Hoffer’s important insights is that it is not poverty that turns someone into a true believer; it is frustration. It is a sense that one deserves far better. It is not surprising that some of those engaged in terrorism are petty criminals.

Hoffer argues “that the frustrated predominate among the early adherents of all mass movements and that they usually join of their own accord”. Among their characteristics is that they may feel they do not fit into their societies. This is not unlikely to be the case for some children of immigrant minorities. Their attachment to the culture of their family’s origin and identification with the culture of their family’s destination are both quite likely to be fragile.

What then does the belief offer? In essence, it offers an answer: it tells the adherents what to think, how to feel and what to do. It provides an all-embracing community in which to live. It offers a reason for living, killing and dying. It replaces emptiness with fullness, and aimlessness with purpose. It offers a cause. This is sometimes noble and sometimes base, but it is a cause, and that is what matters.

“All mass movements generate in their adherents a . . . proclivity for united action,” notes Hoffer. “All of them, irrespective of the doctrine they preach . . . breed fanaticism, enthusiasm, fervent hope, hatred and intolerance”. All demand “blind faith and single-hearted allegiance”.

Secular democracy vulnerable

Communism has waned. So, in many places, has secularism. Religion has taken its place. The moral and intellectual bankruptcy of secular rulers – particularly corrupt secular despots – has encouraged this revival. But western secular democracies are also vulnerable to assaults from true believers in militant Islamism. Wars may control them. But violence will not eliminate them, as the West has learned in both

Iraq

and

Afghanistan

. The enemy is not “terrorism”, it is the idea of which terrorism is the fruit.

Deterring people willing to die is hard. Killing ideas is hard. Killing religious ideas is nigh on impossible. If such ideas are to wane, they will do so only at the hands of more attractive ideas. Possibly, the more extreme might perish of exhaustion. But this could take a long time. Remember that Luther's ideas triggered 130 years of religious wars in Europe. It is a disturbing precedent.

What is to be done? I claim no expertise in this area. But I claim at least an interest: that of a citizen of a liberal democracy, which I very much wish to remain so. My answers are as follows.

First, accept that we are playing the long game of containment.

Second, recognise that the heart of the struggle is elsewhere. The West can help. But it cannot win those wars.

Third, offer the lived idea of equality as citizens as an alternative to violent jihad.

Fourth, appreciate and respond to the frustrations many now feel.

Fifth, accept the need for measures to provide security. But remember that absolute safety is never achievable.

Finally, remain true to our beliefs, since without them we have nothing to offer in this struggle. We must not abandon either the rule of law or the ban on torture. Once we do, we have already lost this war of ideals and ideas.

True believers do, once again, want to do us harm. But the threat they pose is not comparable to the ones that liberal democracy survived in the 20th century. We should recognise the dangers, but not overreact. In the end, this too will pass.

Copyright The Financial Times Limited 2015