SARCELLES, France — From the immigrant enclaves of the Parisian suburbs to the drizzly bureaucratic city of Brussels to the industrial heartland of Germany, Europe’s old demon returned this summer. “Death to the Jews!” shouted protesters at pro-Palestinian rallies in Belgium and France. “Gas the Jews!” yelled marchers at a similar protest in Germany.  The ugly threats were surpassed by uglier violence. Four people were fatally shot in May at the Jewish Museum in Brussels. A Jewish-owned pharmacy in this Paris suburb was destroyed in July by youths protesting Israel’s military campaign in Gaza. A synagogue in Wuppertal, Germany, was attacked with firebombs. A Swedish Jew was beaten with iron pipes. The list goes on.  The scattered attacks have raised alarm about how Europe is changing and whether it remains a safe place for Jews. An increasing number of Jews, if still relatively modest in total, are now migrating to Israel. Others describe “no go” zones in Muslim districts of many European cities where Jews dare not travel.  But there is also concern about what some see as an insidious “softer” anti-Jewish bias, which they fear is creeping into the European mainstream and undermining the postwar consensus to root out anti-Semitism. Now the question is whether a subtle societal shift is occurring that has made anti-Jewish remarks or behavior more acceptable.  “The fear is that now things are blatantly being said openly, and no one is batting an eyelid,” said Jessica Frommer, 36, a secular Jew who works for a nonprofit organization in Brussels. “Modern Europe is based on stopping what happened in the Second World War. And now 70 years later, people standing near the European Parliament are shouting, ‘Death to Jews!’ ”  This is not the Europe of 1938. French leaders have strongly condemned the violence. Chancellor Angela Merkel of Germany this month led a rally against anti-Semitism in Berlin at which she told Germans, “It is our national and civic duty to fight anti-Semitism.”  Europe has seen protests and outbursts of anti-Semitism whenever the Israeli-Palestinian conflict has erupted, and some analysts say this summer’s anger is a cyclical episode that like others will fade away. Some note that the number of reported anti-Semitic incidents this year in France, for instance, is well below some years in the 2000s.  Yet as European support for the Palestinian cause and criticism of Israel have hardened, many Jews describe a blurring of distinctions between being anti-Israel and being anti-Jew.  With Europe still shaking from a populist backlash against fiscal austerity, some Jews speak of feeling politically isolated, without an ideological home. Many left-wing political parties are anti-Israel. Many right-wing parties, some with anti-Semitic origins, are extremist and virulently anti-immigrant. And many Jews who have voted with the Socialist Party in France and Belgium worry that those parties are weak and becoming more dependent on fast-growing Muslim voting blocs.  Even among those inclined to condemn racism in any form, fighting anti-Semitism is no longer seen as a priority, with Jews often perceived as privileged compared with Muslims and other minorities confronted with discrimination.  Many younger Muslims often seem alienated in Europe. Struggling to find work and frustrated by their lack of acceptance, a small but vocal group of them has become inflamed by the politics of the Middle East, especially the Israeli-Palestinian conflict.  European officials are deeply concerned that radical Islam, nurtured in the Middle East, could take root in Europe. Mehdi Nemmouche, a French Muslim arrested in connection with the killings at the Jewish Museum in Brussels, fought as a jihadist in Syria. A French journalist who was held captive in Syria until April said Mr. Nemmouche had been one of his torturers.  “We are a microcosm of the Middle East,” said Philip Carmel, European policy director for the European Jewish Congress. “The Middle East is being imported into Europe.”  Visits to some of the flash points of the summer violence revealed a picture of what Prime Minister Manuel Valls of France has called a “new anti-Semitism.” In Sarcelles, the Paris suburb where pro-Palestinian protests spiraled into riots, the alienation of France’s immigrants and minorities lies just below the surface. In Brussels, the headquarters of the European Union, some secular Jews described a changing atmosphere and questioned whether it was time to leave.  And in Wuppertal, Germany, a city proud of its commitment to religious and ethnic diversity, the attempted firebombing of a synagogue exposed underlying tensions that became even clearer this month when, unexpectedly, a group of Muslim men patrolled a neighborhood wearing makeshift uniforms that said “Shariah Police.”  On the afternoon of July 20, a siege mentality gripped Little Jerusalem, the Jewish commercial district in Sarcelles. A crowd of young Jewish men had gathered at the synagogue as a pro-Palestinian protest was held a few blocks away. France’s Interior Ministry had tried to ban the protest, which spun into a riot. Cars were burning. Young men were throwing rocks as the police fired tear gas. A Jewish-owned pharmacy was set on fire.  “We were all concentrated here to defend the synagogue,” said Levi Cohen Solal, 21, who joined the human cordon outside the synagogue. “Everybody was scared.”  Blocked by the police, the rioters never reached the synagogue, but Sarcelles became a televised symbol of France’s new anti-Semitism — a depiction many local residents did not recognize. A working-class suburb where generations of immigrants are packed into government housing, Sarcelles is a melting pot of religions and ethnicities, where many people speak of a largely peaceful coexistence.  To many residents, the demonstration, which was organized by outsiders on social media, was an indictment not of Sarcelles, but of France. Youth unemployment is soaring, especially in immigrant havens like Sarcelles, and many French-born children and grandchildren of immigrants have become alienated from French society.  “They have a real hatred against the state,” said Bassi Konaté, a city social worker, who added that many of the protesters came from poorer districts nearby. “A big proportion of these people feel neglected. A lot of these people don’t know anything about Gaza. But they want to confront the police.”  An early sign that these broader resentments were morphing into more open expressions of anti-Semitism came with the emergence several years ago of Dieudonné M’bala M’bala, a French comedian who lashed out at Jews and played down the Holocaust. He has since allied himself with Jean-Marie Le Pen, the 86-year-old founder of the far-right National Front, who this summer used an apparently anti-Semitic pun, which alluded to Nazi crematories, as a riposte to a Jewish critic. Many of the comedian’s shows have since been banned in France, but his popularity has continued to rise, unnerving many Jews.  “For the past four or five years, we have felt a growing insecurity,” said David Harroch, who runs a Jewish bookstore in Little Jerusalem. “My customers tell me how worried they are about the climate here, the situation. A lot of people have left.”  Israeli officials predict that as many as 6,000 Jews will migrate from France this year, a stark reversal from the 1950s, when Sephardic Jews, Arabs and others began arriving in Sarcelles from North Africa. A booming economy made work plentiful.  But during France’s recession in the late 1970s, the city’s ethnic groups became pitted against one another for limited public resources. Rahsaan Maxwell, a political scientist who has studied Sarcelles’s ethnic groups, said the Sephardic Jews had incurred resentment because they were better organized and able to mobilize politically to win certain perks from the elected local council: a special Jewish section in the local cemetery, widening of a road in front of the main synagogue, kosher offerings at an annual city dinner for the elderly, and segregated swimming hours for men and women at a city pool.  In his 2012 book, “Ethnic Minority Migrants in Britain and France,” Mr. Maxwell wrote that Sephardic Jews became so influential that “when Israel was at war with Lebanon in the early 1980s, Sephardic Jewish activists in Sarcelles were aggressive about using it as a litmus test for local politicians to see whether they supported Israel and the Jewish people.”  Yet many Jews and Muslims born in that era grew up together without rancor in government housing. Not far from one of the city’s storefront mosques is a small Superette grocery owned by a Muslim family. One of the owners, Abdel Badaz, recently stood behind the counter with a childhood friend, Mickaël Berdah, 36, a Jew whose family emigrated decades ago from Tunisia. They both criticized the riot as the work of young troublemakers.  “When you’ve grown up in the neighborhood, and you know everybody, there isn’t that kind of hate,” Mr. Berdah said. “When there is that kind of hate, it is at the roots, something about the way parents have educated their children.”  Later, near the grocery, a tall teenager pedaled his bicycle toward two journalists and shouted at them to leave, saying the media had lied about Sarcelles. The youth, Diakité Ismael, 19, the French-born son of Senegalese immigrants, soon calmed down and, like others, argued that there was no animosity in Sarcelles between local Muslims and Jews.  “Look,” he said, as a bearded Jewish man in a dark suit and skullcap walked by, “there’s one.”  But when asked about Gaza, Mr. Ismael became agitated, rambling and warning that the world was hurtling toward a catastrophe. He said he had seen video of an Israeli bomb hitting a funeral in Gaza. “Somehow, some Jews control politics, information, business and finance,” he said. “I’m not talking about the Jews here. I’m talking about Jews in general.”  “Jews, in general,” he added, “only let you see what they want you to see.”  Music rose from the center of Brussels on Sunday, with joggers and bicyclists moving freely down city streets as the seat of the European Union held its annual no-car day. It had the giddy air of a street fair, if less so for the city’s Jewish organizations, which the police had placed under heightened security since two recent incidents.  The first happened the previous Sunday, Sept. 14, which marked the European Day of Jewish Culture. As people gathered to dedicate a plaque at a Holocaust memorial, youths hurled stones and bottles until the police arrived. Three days later, a fire erupted on an upper floor of a synagogue in the city’s Anderlecht district; the authorities are investigating the incident as arson.  It was the May shooting at the Jewish Museum in Brussels — and the subsequent arrest of Mr. Nemmouche — that attracted international attention, as four people were killed, including two Israelis. But there have been smaller incidents that received less notice: a Turkish shop owner in Liège who posted a sign saying he would serve dogs but not Jews, a voice on the intercom of a commuter train that announced a stop as "Auschwitz" and ordered all Jews to get off.  “This summer, I started to see the world in a different way,” said Marco Mosseri, 31, a native Italian who works in the automotive industry in Brussels. “I was scared. I spent several nights without sleep. For the first time, I was thinking that maybe I could die from my religion.”  With its chocolate shops, Trappist beers and gray gloom, Brussels is the center of Europe’s sprawling bureaucracy, a symbol of the loathed policies of austerity. But Brussels also embodies the demographics transforming much of urban Europe, with generations of Muslim immigrants and their descendants now representing roughly a quarter of the population.  The Jewish community is small, about 20,000 people, most of them assimilated, secular Jews like Mr. Mosseri, who usually do not draw attention to their heritage. (A recent report issued jointly by two European Jewish organizations found that 40 percent of European Jews hide their Jewishness.) Now some secular Jews say they have stopped wearing a necklace with the Star of David, or allowing their children to wear T-shirts for a Jewish summer camp on public buses or trains.  And since the start of the conflict in Gaza this summer, many describe social media, especially Facebook, as a swamp of hatred.  “I have friends who are never political and they are posting things about Gaza every day,” said Ms. Frommer, the employee of the nonprofit organization. “It seems like an obsession. Is your obsession because you want to save children, or because you have a problem with Jews?”  In a city so devoted to politics, the issue of Israel can seem unavoidable to some Jews, even those who strive to be apolitical or tend to be critical of Israeli policy. Ms. Frommer grew up in Brussels, but then left for college in Britain, followed by a long stint working in Cambodia. When she returned to Brussels four years ago, she was struck by how much more polarized life seemed. Her Jewish friends were sticking closer together as office chatter now sometimes bore a sharper edge.  This summer, one of her Belgian colleagues repeatedly mentioned the Israeli-Palestinian conflict. “He would often try to bring up the subject when I tried not to,” she said. “Then the subject would shift from Israel to Jews. Then it was, ‘Were there really six million Jews killed in the Second World War?’ ”  Nor was the comment isolated. There have been signs that anti-Jewish sentiment transcended the immediate backlash against the Gaza war. In Hungary, the rise of the far-right Jobbik party has brought concerns that anti-Semitic views are gaining mainstream traction.  In Italy, extreme right-wing activists were blamed for a flurry of anti-Jewish graffiti, including Nazi swastikas, on buildings in various cities. In Rome, f liers calling for a boycott of at least 40 Jewish-owned stores appeared last month with the signature of the far-right group Vita Est Militia. Italian investigators were also looking into whether such far-right parties were building alliances with extremist left-wing groups.  In Brussels, several pro-Palestinian marches were held this summer, most of which were peaceful, but a few bore an anti-Semitic edge, including shouts of “Death to Jews!” While Belgian politicians quickly condemned the shooting at the Jewish Museum, some Jews felt the response to the protests, including that of the center-left Socialists, was tepid at best.  “The Socialist Party is afraid, because of the votes here in Belgium,” said Dr. Maurice Sosnowski, an anesthesiologist and prominent Jewish leader in Brussels. “In Belgium, they are not willing to speak loudly, because there are a lot of Muslims.”  In the nonprofit world of Brussels, the politics of Israel, which some on the European left view as essentially the pursuit of racist objectives against Palestinians, have made it difficult to keep the fight against anti-Semitism high on the agenda.  “Some see it in conflict with the anti-racism movement,” said Robin Sclafani, director of the Brussels-based group A Jewish Contribution to an Inclusive Europe. The organization, also known as CEJI, provides anti-discrimination training to teachers, social workers and others. Ms. Sclafani said she now receives numerous requests for training sessions to combat discrimination against Muslims, yet there is little interest in workshops on anti-Semitism.  “Nobody comes,” she said, adding that she has started pairing the sessions together.  Michaël Privot, director of the European Network Against Racism, said that blaming only the Islamic fringe for anti-Semitism discounted academic studies that show how deeply ingrained it remains among all Belgians — as well as other Europeans — and risked giving a free pass to right-wing extremist groups.  “You have, basically, a golden opportunity for the right fringe to blame it on Muslims and claim innocence,” Mr. Privot said.  On Sunday, as much of the city enjoyed the car-free streets of Brussels, a group of secular Jews gathered at the headquarters of CEJI with a visiting journalist to discuss ordinary life for them. Because of the heightened security alert, three plainclothes police officers were stationed in the lobby.  Like others in the room, Ms. Frommer described a growing sense of isolation. As a teenager, she participated in left-wing Jewish youth groups, but she said some of her friends were now attracted to the extremist right-wing party Vlaams Belang. The party is led by Filip Dewinter, an outspoken critic of Muslim immigration who has been courting Jews, despite his party’s past links to anti-Semitism.  “I would never be able to vote for someone like that,” Ms. Frommer said. “But some people are now. It is more and more legitimate to vote right wing.”  She and others said that many friends were talking of moving to Canada or to the United States, if not Israel, even though they are uncertain whether their anxieties are fully justified.  “These are people with good jobs,” she said. “And life is comfortable here. The big question is: Should we be paranoid or not?”  The news spread quickly in the early morning of July 29 among the Jews of Wuppertal, Germany. Someone had tried to firebomb the city’s synagogue. The devices had failed to ignite, leaving the building with little damage, unlike the collective psyche of its members.  “For Jews in Germany, especially for us, this has very, very deep meaning,” said Artour Gourari, a local businessman and synagogue member. “Synagogues are burning again in Germany in the night.”  Nowhere in Europe has the postwar imperative to fight anti-Semitism been more complete — and more intertwined with national redemption — than in Germany. In Wuppertal, a manufacturing center, the city’s synagogue was burned in 1938 during the two-day rampage known as Kristallnacht, when an anti-Jewish pogrom swept across Nazi Germany.  After the war ended, Wuppertal’s Jewish community had no synagogue and, with only 60 members, seemed destined for extinction. But with the collapse of the Soviet Union in the 1990s, the German government opened the country to persecuted Soviet Jews, and soon refugees from Uzbekistan, Belarus, Ukraine and Russia had settled in Wuppertal. The local Jewish population reached 2,500. The presidents of Germany and Israel attended the 2002 inauguration of the new synagogue.  Now a police van is stationed around the clock in a small park across from the synagogue. The police have arrested three suspects in the firebombing attack, all Palestinians, including one from Gaza, as well as a 17-year-old refugee. The refugee has lived in Wuppertal for two years, among the different Muslim communities of Turks, North Africans and asylum seekers from Egypt, Syria, Jordan and Lebanon.  Until the synagogue attack, Wuppertal officials had taken pride in the peaceful coexistence of so many religions and ethnicities. Many of the older Muslims had arrived in the 1960s for work but assumed they would eventually return to their home countries. Now a third generation, born in Germany, is growing up with different expectations, as well as a sense of alienation.  “They have to justify why they don’t fully belong to the society,” said Samir Bouaissa, a local Muslim leader.  One of the local high schools is named after a famous Jewish poet, Else Lasker-Schüler, and is commonly called “The School Without Racism.” Yet two recent graduates described rising tensions in the multiethnic student body, including resentment by some Muslim students over a sister-school arrangement with a school in Israel. This summer, during the Gaza crisis, several Muslim adolescents began circulating anti-Israel posts on social media.  This one “got shot yesterday,” said a Facebook post from Gaza shared by a student. It showed a photograph of a female Israeli soldier and added an obscenity. The student added his own postscript: “You get what you deserve.”  Antonia Lammertz, 19, a recent graduate, said only a small minority of students were extreme but that a softer bias was common even among the mainstream. “In my school, to be called a Jew was to be cursed, or insulted,” she said, noting a problem that officials have tried to root out at many German schools.  City religious leaders reacted quickly after the synagogue attack. Imams and Christian ministers rushed to the building to pledge support. More than 300 people came to a hurriedly organized peace meeting the next day.  “People were shocked,” Mr. Bouaissa said. “A threat against one of our religious houses is a threat against all of us.”  Earlier this month, the city’s religious leaders, including many Muslims, got another shock: a small group of men, one only 19, spent an evening walking through a Muslim neighborhood, lecturing young people about vices like gambling (while apparently not mentioning Jews). They were wearing orange jackets that read “Shariah Police.” The leader was a Salafist, Sven Lau, who called the event a one-time publicity move to stir more “Islamic discussion.”  That, it did. Local prosecutors filed charges. German officials, including Ms. Merkel, reacted with a blend of shock, indignation and alarm, while mainstream Muslims also protested. And local neo-Nazis responded with their own patrol, dressing in red pullovers and pledging to protect the public from Islamists.  For Leonid Goldberg, the community leader of the Wuppertal synagogue, the emergence of a radical Islamic fringe is less a surprise. Just four days before the synagogue attack, someone had spray-painted “Free Palestine” on the front wall of the building. In recent years, Mr. Goldberg has used a celebration of Rosh Hashana at the synagogue — an event attended by elected officials and religious leaders of the city, including Muslims — to warn about rising anti-Semitism among extremist Muslims in the city.  “No one wanted to hear that,” he said.  Aurelien Breeden and Maïa de la Baume contributed reporting from Sarcelles, and Katarina Johannsen from Wuppertal, Germany.  A version of this article appears in print on September 24, 2014, on page A1 of the New York edition with the headline: Europe’s Anti-Semitism Comes Out of Shadows. Order Reprints|Today's Paper|Subscribe
In the wake of the conflict in Gaza, three communities became flash points of violence and began contending with hatred they thought was buried in the past.