IS IT correct to find parallels between violent white supremacism and neo-Nazism on one hand, and the nihilist fury of ultra-militant Islam on the other? A Franco-American scholar, Scott Atran, is convinced that these deadly phenomena are two sides of the same coin. Unless people grasp that point, he thinks, our ability to cope with either scourge may be limited.

Of course there are superficial resemblances which anyone can see. In August, when a fanatic drove his car into a group of liberal, anti-racist protesters in Charlottesville, Virginia, he was copying a tactic that had already been used by self-styled warriors for Islam in at least four European countries.

But Mr Atran, who holds academic posts in Britain, France and America, sees deeper resemblances. He makes the point in an essay for Aeon, a forum for elaborate intellectual arguments, drawing on a series of his own academic investigations.

In his view, both kinds of fanaticism reflect both the failure of the liberal democratic order to inspire anyone to defend it, and the insidious attractiveness of ideologies which challenge that order. What makes these ideologies appealing is not their content but the strong collective identity they offer. They create peer groups that promise their own members such admiration that it can seem like sufficient reason to lay down one’s life. By contrast, surveys suggest that very few people, these days, feel inclined to give up their lives for democracy.

His argument is a provocatively pessimistic counterpoint to one aired 25 years ago by Francis Fukuyama, the American thinker who believed then that the collapse of Soviet communism, and of other tyrannies like apartheid in South Africa, portended “the end of history”. In other words: a state of affairs in which there was no serious alternative to free markets and free ballots, underpinned by transparent rules.

Citing his own research, along with that of colleagues in France, Spain and Morocco, Mr Atran finds that “there is little willingness to make costly sacrifice for democracy, especially compared with the willingness to fight and die for jihad in Europe.”

Statements by Western leaders to the effect that “our values will prevail” have been glib, Mr Atran concludes. As he puts it:

Our wide-ranging interviews and psychological experiments have uncovered not a “clash of civilisations”…but civilisation’s unravelling, as young people unmoored from traditions flail about in search of a social identity that gives personal significance and glory.

Both jihadism and white-nativist fascism have successively presented themselves as answers to that search, in Mr Atran’s view. And this is hardly the first time in history when disruptive economic growth, technological advances and the fading of old certainties have driven people to terrorism. As Mr Atran recalls, there was a rash of high-level assassinations inspired by the anarchism that started in the late 19th century, from Russia to America. And in the 1920s, the Ku Klux Klan enjoyed a surge in membership, reaching 4m.

Among today’s jihadists and far-right fanatics, there is an apocalyptic belief that a final reckoning with their opponents is not only inevitable, but that it should be accelerated through actions that undermine conventional authority. From that perspective, almost any act of violence can be justified. As an example of such thinking, Mr Atran quotes the grim words of a white-supremacist leader he met: “Evil is the failure to recognise the necessity of race war.”

The scholar argues that many Western elites are still in a state of Fukuyama-like optimism which underestimates the threat posed by both kinds of extremism. At this year’s World Economic Forum in Davos he “had the impression that most people in attendance thought that the recent surge of jihadism and xenophobic ethno-national populism were just atavistic blips in the ineluctable progress of globalisation.”

If his argument is onto something, then at least this much follows. It is often said, with some degree of justice, that mainstream Muslim leaders should be even more energetic in denying any shred of legitimacy to terrorism, and in offering an attractive alternative vision of their faith. But what of the historically Christian world? White supremacists may or may not claim to be fighting for Christian (or even Judeo-Christian) values. But it surely behoves anybody who holds or aspires to moral leadership in the Western world, from clerics to politicians to public intellectuals, to be ultra-careful not to give any sort of cover to nativist fanaticism. And to offer a compelling, alternative account of which Western values are actually worth defending.