When up to a dozen world leaders and roughly 1.5 million people gathered in Paris on Sunday to mourn the murder of 10 editors and cartoonists of the satirical newspaper Charlie Hebdo and seven other people by three French-born Islamic radicals, they wanted to demonstrate that Europe will always embrace liberal and tolerant values.

But the more telling event may turn out to be a counter-rally that took place at a 17th-century town hall in Beaucaire, France, that was led by Marine Le Pen, the leader of the far-right National Front. In Beaucaire, the crowd ended Le Pen’s rally by singing the French national anthem and chanting, “This is our home.”

Le Pen is at the forefront of a European-wide nationalist resurgence — one that wants to evict from their homelands people they view as Muslim subversives. She and other far-right nationalists are seizing on some legitimate worries about Islamic militancy — 10,000 soldiers are now deployed in France as a safety measure — in order to label all Muslims as hostile to traditional European cultural and religious values. Le Pen herself has likened their presence to the Nazi occupation of France.

Le Pen herself espouses an authoritarian program that calls for a moratorium on immigration, a restoration of the death penalty and a “French first” policy on welfare benefits and employment.

Long after World War Two, fascism is a specter that still haunts the continent. But whether Le Pen’s stances — and those of other nationalist leaders in Europe — qualify as fascist is questionable. The borderline between the kind of populism they espouse and the outright fascism of the 1920s and 1930s, when Adolf Hitler and Benito Mussolini espoused doctrines of racial superiority, is a slippery one. Scholars continue to debate whether Mussolini was even fascist — or simply an opportunistic nationalist.

The real aim of today’s would-be authoritarians — politicians who appeal to the public’s desire for an iron hand — is to present themselves as legitimate leaders who are saying what the public really thinks but is afraid to say. And these far-right leaders are indeed increasingly popular.

The card they are playing is populism presented as an aggrieved nationalism. They depict Europeans as victims of rapacious Muslim immigrants. Le Pen, Britain’s Nigel Farage of the U.K. Independence Party and others aim to come across as reasonable and socially acceptable, while sounding dog whistles to their followers about immigrant social parasites who are either stealing jobs from “real” Europeans or living off welfare.

Unlike in the 1930s, Le Pen and her compatriots do not deliver spittle-beflecked speeches calling for the extermination of other races. Le Pen avoids the kind of demagogic language used by her father Jean-Marie Le Pen, a former intelligence officer in France’s vicious war in Algeria, who called the Holocaust a mere “detail.”

Indeed, Le Pen is now wooing some Jewish voters frightened of terrorism. She is essentially offering a slicker form of authoritarianism that brands Muslim immigrants as a new internal enemy. The new nationalist argument is that the individual countries of Europe must safeguard their traditional values by rejecting the liberal chimera of a single, united Europe with open borders.

This has paid off for Le Pen’s Front National, which in May led the field in France’s European Union elections, drawing 25 percent of all votes. And these numbers are only predicted to increase.

After World War Two, nationalism went into remission in Europe. Until recently, nationalist parties were largely regarded as a noisy but fringe phenomenon. The notion that they would gain public respectability — let alone wield power — seemed outlandish. No longer.

In France, Germany, Greece, Sweden, the Netherlands and Britain, nationalist leaders are seizing on the tragic events in France to argue that they have been right all along. They argue that the open borders and liberal tolerance championed by the European Union are allowing a virulent jihadist virus to infect their countries.

Le Pen insisted the day after the Paris attacks that Islam is an “odious ideology” In that same Jan. 9 address, she said “The absolute rejection of Islamic fundamentalism must be proclaimed loudly and clearly” and called on French President Francois Hollande to suspend the Schengen Accords that allow for visa-free movement inside Europe.

Meanwhile, Alexander Gauland, a leading member of the libertarian party Alternative for Germany, maintains, “Everyone who has until now laughed or scoffed at the apprehensions of people of a looming Islamic threat are being punished by this bloodshed.”

And Farage, of the U.K. Independence Party, which wants to leave the European Union, says that a jihadist “fifth column” exists in France, one that is the result of multi-cultural policies. In the May EU elections, his party bested both the Conservative and the Labour Party, winning 28 percent of the vote, a big jump from its 16.5 percent in 2009, the last EU election. Twenty years ago, it only drew 1 percent.

The vitality of all these parties is a direct result of the failure of mainstream political elites. Exhibit A is the self-destructive austerity policy that Germany under Chancellor Angela Merkel has espoused. Haunted by the memory of the soaring inflation that helped destroy Germany’s post-World War One democratic Weimar Republic — leading to Hitler’s rise — Berlin has demanded budget cuts and opposed stimulus programs that could help revive the struggling economies of southern Europe.

This is perverse. It has had the effect of miring the eurozone in unemployment and deflation — thereby helping create conditions reminiscent of the 1930s, when economic misery helped radicalize the middle and working classes.

Today, a new generation of leaders on the right has seized on Europe’s economic malaise to argue that the real culprit is Islamic immigrants taking jobs away from the native-born. The underlying sentiment — the demonization of an “out” group — recalls the wave of anti-Semitism that helped propel fascist political parties to triumphs during the 1930s.

The credo of nationalist parties today is that Europe, the cradle of Western Civilization, is directly threatened by a new influx of Muslims intent on reenacting the Islamic invasion of Europe that took place in the eighth century and was only stopped by Charles Martel at the Battle of Poitiers in 732. It’s a message that’s attracting new adherents — some of them Jews, who feel threatened by Muslims.

Skepticism of European unity and immigrants has also proved a potent political move in France’s neighbor, Germany. The anti-euro Alternative for Germany party has entered state parliaments in Thuringia, Saxony and Brandenburg in the past year and its leading figures are making common cause with anti-immigrant groupings.

In Dresden, for example, weekly rallies against immigrants are taking place under the rubric Patriotic Europeans Against the Islamization of the Occident”– PEGIDA. Last October the turnout was roughly 500. At least 25,000 marched Monday — despite condemnations from mainstream politicians, including Merkel.

In the Netherlands, populist leader Geert Wilder’s Freedom Party is leading the polls. In Greece, the neo-Nazi Golden Dawn Party entered parliament in 2012 with the slogan, “So we can rid this land of filth.” In Sweden, the anti-immigrant Sweden Democrat Party vaulted to 13 percent of the vote in 2014.

Though parties of the right have a history of squabbling with one another, they have begun to cooperate in the European parliament. If Le Pen were to win the French presidency in 2017, it could spell the end of the European Union and perhaps return the continent to a collection of feuding nation-states.

Franco-German cooperation, which has been at the heart of and essential to the European Union since its inception, would come to an abrupt end. The European Union has functioned as a way for Germany to leave behind an assertive nationalism that led to two world wars and create a new and peaceful identity as part of a democratic Europe. If La Pen wins in 2017 many could view it as a repudiation of that vision. The long shadows cast by the Nazi past would make it too difficult for any German chancellor to work with an authoritarian leader like Le Pen in the heart of Europe.

Certainly Europe’s democratic institutions are far stronger than they were in the 1930s. But this is no reason for complacency.

A revived European leadership that addresses immigration and the economy is essential — or the decades-long dream of a united Europe will disintegrate, to be replaced by combative nation-states headed by nationalist leaders. Merkel and other leaders on the continent, for example, will have to allow Britain to opt out of the European Union’s insistence on free movement within EU borders.

For British Prime Minister David Cameron intends to strengthen his island-nation’s border controls. He wants to tightly restrict EU immigrants’ rights, prohibiting claims for British benefits or public housing for four years and deporting those who do not get a job within six months Otherwise, he will be outflanked on the right by Farage’s U.K. Independent Party, with the possibility of British voters approving a referendum for withdrawal from the EU.

The demons that European leaders tried to suppress after 1945 are back. It won’t be easy to exorcise them.

PHOTO (TOP): Members of DUEGIDA, Duesseldorf’s section of anti-immigration movement Patriotic Europeans Against the Islamization of the West (PEGIDA) demonstrate in Duesseldorf, January 12, 2015. REUTERS/Ina Fassbender

PHOTO (INSERT 1): Journalists surround Marine Le Pen, France’s National Front political party head, who reacts to results after the polls closed in the European Parliament elections at the party’s headquarters in Nanterre, near Paris, May 25, 2014. REUTERS/Christian Hartmann

PHOTO (INSERT 2):Marine Le Pen (C), France’s National Front political party leader, smiles after delivering a speech at their congress in Lyon, Nov. 30, 2014. REUTERS/Robert Pratta

PHOTO (INSERT 3): Part-time and temporary arts workers, known as “intermittents,” hold coffin-shaped cardboard boxes as they demonstrate over government plans to accept the unemployment insurance agreement in Marseille, June 26, 2014. REUTERS/Jean-Paul Pelissier

PHOTO (INSERT 4): Supporters of anti-immigration movement Patriotic Europeans Against the Islamization of the West (PEGIDA) hold flags during a demonstration in Dresden, January 12, 2015. REUTERS/Fabrizio Bensch