In many European countries, including France and Germany, the number of anti-Semitic crimes committed this year already exceeds the total for 2013. It would be an exaggeration to say that Europe is no longer hospitable to Jews. But German Chancellor Angela Merkel had good reason this week to publicly fret about “young Jewish parents who wonder whether they can raise their children in Germany.” Europe’s political climate is more hostile to Jews now than at any time since the second intifada.

Rising anti-Semitism among Europe’s Muslims is one reason for this change. Some protests against the latest war in Gaza, such as a recent march in Gelsenkirchen that culminated in calls of “Jews to the gas!” prominently featured anti-Semitic imagery or slogans. Others, such as the attack on a synagogue in Paris’ Maraisdistrict this past July, ended in outright violence.

But to claim that the rise of Muslim anti-Semitism is the main culprit for the changed climate -- as the German journalist Jochen Bittner did this week in The New York Times -- is to pin the blame on a small minority while overlooking that anti-Semitism has also grown among the majority. According to a recent Pew Research Center study conducted in Germany, although around 6 percent of the population is Muslim, 25 percent of people readily express unfavorable views of Jews; meanwhile, in Spain, where less than 3 percent of the population is Muslim, close to 50 percent of the population do the same. Although levels of anti-Semitism may be higher among Muslims than among Christians, a European anti-Semite remains far more likely to be Christian than Muslim.

Tensions between Muslims and Jews are a real problem, and one that has been swept under the carpet for too long; but an even greater problem is the tendency of wily politicians to play Jews and Muslims against each other for purposes of their own. The real question of Europe’s future is not whether Muslim immigrants will learn to tolerate Jews, but whether, in countries such as Sweden, Italy, and Poland, the majority can learn to think of Muslims and Jews as true members of the nation.

THE POPULIST PIVOT

Most Europeans are reluctant to believe that somebody of Turkish or North African origin can qualify as truly German, Belgian, or French. Indeed, even many Europeans who consider themselves open to immigration tend to demand that immigrants abdicate their prior identities and assimilate entirely into local customs. For a long time, right-wing populists tried to exploit these attitudes by mounting a frontal attack on the idea of a liberal, diverse society: their opposition to immigration was but a launching pad for a musty vision of national purity, which harked all the way back to fascism.

The appeal of this form of populism always remained limited. Most Europeans like to think of themselves as secular, modern, and tolerant. Although they reject the idea that their homelands should accommodate the cultural and religious priorities of new arrivals, the version of that homeland they seek to defend is, in its own way, rather open-minded and diverse. They may grow defensive when immigrants seek to leave a cultural mark on the country, but they are personally open to many of the world’s cultural offerings, from sushi to yoga.

A new generation of far-right leaders, such as Geert Wilders in the Netherlands and Marine Le Pen in France, have taken this lesson to heart. They haven’t stopped exploiting resentment against Muslim immigrants. But they have dressed up that resentment in new clothes. Instead of calling for an assault on modern, liberal society, they argue that Muslim immigrants -- through their supposed rejection of free speech, their insistence on sharia law, or their intolerance of Jews, women, and homosexuals -- imperil that very order. European right-wing extremism has transformed into what one might call liberal Islamophobia.

To signal how different they are from their predecessors, liberal Islamophobes also embrace Jews. There is a clear logic to this strategy. Because of their past persecution, Europe’s Jews have become the continent’s moral arbiters -- mainstream society’s litmus test for tolerance. To ward off accusations of racism, populists across the continent -- from the British politician Nigel Farage to the best-selling German writer Thilo Sarrazin -- have thus learned to preface their incendiary remarks about Muslims with a marker of tolerance and enlightenment: lavish praise of Jews and Judeo-Christian civilization. For the same reason, Le Pen and other populists take every opportunity to shine a spotlight on instances of anti-Semitic violence perpetrated by Muslims. Doing so allows them to claim the mantle of tolerance even as they sow hatred.

Populists’ repeated invocation of Jews has proved effective. By paying lip service to tolerance and an open society, parties such as France's Front Nationalhave managed to move from the political fringes to the mainstream. But their philo-Semitism remains insincere. European populists -- and their supporters -- are not only eager to speak their minds about the Muslim immigrants they had long disliked; they are also growing impatient with what they perceive as the desire of Europe’s Jews to pass judgment on the majority. The very same revival of nationalism that has been fueled by their invocation of Jews can, in this way, quickly turn into anti-Semitism.

EUROPE'S MORALITY PLAY

In many European countries, Jews have long represented an irksome reminder of the blemishes on the nation’s moral standing. This is most obviously the case in Germany, where Jews are widely seen as flesh-and-blood embodiments of the darkest hour in the nation’s history -- a chapter that a younger generation of Germans, impatient with the ubiquitous memorials attesting to their nation’s past crimes, is determined to make a less prominent part of public life. But the same goes for countries that once saw their own history in unambiguously positive terms: whether in Poland, Sweden, or France, past treatment of Jews complicates long-standing narratives about heroism in World War II.

Given the strange role Jews have been assigned in Europe’s societal morality play, it gives nationalists special comfort to claim that Jews are ultimately no better than the fascists and collaborationists of the continent’s past. By showing that Jews are themselves capable of perpetrating violence, they hope to lighten their nations’ heavy historical burdens. When Israel began bombing Gaza this summer, European nationalists seized the opportunity to do just that.

As a result, the composition of the populists’ coalition has shifted once again. For much of the past decade, the dominant tendency was for such groups to seek an alliance with Jews. In recent months, by contrast, Jews have been kicked out and replaced with Muslims. Increasingly, both populists and Muslim immigrants blame -- and punish, sometimes violently -- European Jews for the actions of the Israeli government. This tendency has long been a feature of Europe’s left; witness the cinema in London that recently canceled a Jewish film festival to protest the bombings of the Gaza Strip. Over the last several months, it has also reared its ugly head among Europe’s right; a well-known columnist in the Spanish newspaper El Mundo, for example, wrote that events in Gaza explain why Europe’s Jews “have so often been expelled.”

But this constellation, too, is likely to remain short-lived. As the Gaza conflict fades from memory, talk of Europe’s Judeo-Christian roots is likely to make a comeback. Since it is so tempting to play Muslims and Jews off against each other, and the millions of Muslim immigrants pose a far more numerous threat to European identity than the continent’s remaining Jews, liberal Islamophobes will soon rediscover their insincere philo-Semitism.

MAJORITY RULES

The only way to prevent these endless and destructive pendulum swings is to convince Europeans to broaden their conception of national identity. They need to accept that a true Austrian can hail not only from Innsbruck but also from Istanbul and that imported practices that can enrich local culture include not only sushi and yoga studios but also halal meat and minarets. Whether Europeans are able to change their self-conception in this way remains a decisive -- and still undecided -- question for the continent’s future.

Far from being mere playthings in the majority’s shifting priorities, Jews and Muslims can try to reclaim some agency of their own in shaping this future. To do so, they will have to keep in mind that their interests overlap to a surprising degree: a nationalistic Europe that maintains a homogeneous conception of the nation will wind up being inhospitable to both groups. So far, Muslims and Jews have been surprisingly successful at working together. Jewish federations habitually defend Muslims against racist attacks by right-wing politicians. Even as parties, including Le Pen’s Front National,have disavowed anti-Semitism, they have refused to cooperate with right-wing populists. Similarly, most Muslim federations in Europe have, in recent months, remained unequivocal in their condemnation of attacks on Jews.

But there are also warning signs that Muslims and Jews could become willing participants in the political games of populists. Anti-Semitism among Muslim immigrants is real and growing; the number of violent attacks on Jews perpetrated by Muslims is on the rise. Meanwhile, a few well-known Jewish intellectuals, including Alain Finkielkraut in France and Henryk Broder in Germany, have been flirting with increasingly Islamophobic positions; the German Jewish writer Ralph Giordano even condemned plans for a large mosque in Cologne as a “declaration of war.” In light of the ugly confrontations of recent months, it’s conceivable that these voices will ultimately prevail, setting Jews and Muslims against each other at a crucial moment in the development of European identity.

It is the majority, however, that faces the most consequential choice. For all the seductive rhetoric of liberal Islamophobes, an open society cannot be built on a foundation of exclusion. If ordinary Europeans and their political representatives give in to the temptation of lauding Jews the better to exclude Muslims -- or, for that matter, lauding Muslims the better to exclude Jews -- they will wind up with a society that is a lot less tolerant and diverse than they wish for.