A surprising number of people have responded to the bloody slaughter in Paris by saying we shouldn’t have riled them up. “I don’t condone murder,” the argument goes, “but it’s wrong to provoke people by insulting their religion.”

So, what about the slaughter of Jewish shoppers in the kosher supermarket? What did the Jews do to rile them up?

Well, some people know. Gaza, etc. Nothing justifies the slaughter of innocent civilians, of course, but Israel’s atrocities are also a provocation.

In fact, for large parts of the world, Israel’s very existence is a provocation. And for Islamists, killing Jews is God’s work.

“As far as I am concerned, I feel I am Charlie Coulibaly,” declared Dieudonné, the anti-Semitic French comedian, on his Facebook page. He was referring to terrorist Amedy Coulibaly, who gunned down four Jews at a kosher supermarket. Dieudonné, whose appearances and videos feature long rants against Israel and the Jewish lobby, is wildly popular among young French North Africans.

Since the attacks in France, a lot of people have been warning about a backlash against Muslims that could strengthen Europe’s far right and possibly create a new brand of neo-Nazi threat. But the real threat to Europe comes from the kind of angry, disaffected young Muslims who regard Dieudonné as a hero.

France’s leaders are now speaking bluntly about this. Prime Minister Manuel Valls declared Saturday that France is now at war against radical Islam. “There is a new anti-Semitism in France,” he told The Atlantic’s Jeffrey Goldberg. “We have the old anti-Semitism, and I’m obviously not downplaying it, that comes from the extreme right, but this new anti-Semitism comes from the difficult neighbourhoods, from immigrants from the Middle East and North Africa, who have turned anger about Gaza into something very dangerous. Israel and Palestine are just a pretext. There is something far more profound taking place now.”

France’s Jewish population of about 500,000 is less than 1 per cent of the country’s population. Yet Jews are all too often targeted by hate crimes, many of which are committed by Muslims. In 2012, seven people, including three children, were gunned down by Mohammed Merah, an anti-Semitic French citizen of Algerian extraction. Last year, four people were killed at the Jewish Museum in Belgium, allegedly by a French national. Last summer, a pro-Palestinian mob torched Jewish shops in the Paris suburb of Sarcelles. By comparison, hate crimes against Muslims are relatively minor, mostly crimes against property.

On a recent tour of synagogues in Le Marais, the old Jewish quarter of Paris, I asked some of our guides about the future for Jews in France. They were pessimistic. Thousands of Jews have left in recent years and the exodus is increasing. In the wake of the terrorist attacks, France has sent 10,000 troops to guard Jewish schools and synagogues and other sites, but they can’t guard everybody all the time. And they can’t change the minds of the fanatical young men who have embraced Islamic extremism. That will take a revolution within Islam itself.

“I say and repeat, again, that we are in need of a religious revolution,” Egyptian President Abdel Fattah el-Sisi declared on New Year’s Day. “You imams are responsible before Allah. The entire world is waiting on you. The entire world is waiting for your word … because the Islamic world is being torn, it is being destroyed, it is being lost. And it is being lost by our own hands.”

But even if it comes, the revolution against extremism is going to take a while. Meantime, Mr. Valls is tragically correct: We’re at war.