SEVRAN, France — As more than 1.5 million people, including 40 world leaders, converged on Paris on Sunday to rally for unity after terrorist attacks that left 17 innocent people dead, three young men in tracksuits and hoodies lounged outside a fast-food restaurant 10 miles north of the city in Sevran, one of France’s poorest suburbs.

Mehdi Boular, 24, who said he was married with two children, and two of his friends, did not attend Sunday’s rally.

“We’re Muslims,” Boular said. “They might have killed us if we’d gone.”

But even though the flags of Algeria, Morocco, and Tunisia were flying at the rally in Place de la République and Muslims were well represented among the marchers Sunday, Boular said the attacks in Paris were part of a plot masterminded by Jewish conspirators.

“The Kalashnikovs, the identity cards the [killers] supposedly left behind, it was all staged,” said Boular, as his friends nodded in agreement. “It was a conspiracy designed by the Jews to make Muslims look bad. We’d rather just stay where we are.”

No use arguing. No use pointing out that one of the terrorists murdered four Jews. Conspiracy theories have their own unassailable logic, and this is a world apart from the displays of unity in Paris after the carnage of last week. French newspapers reported that some students in these neighborhoods—as well as other heavily Muslim areas near cities like Lille—refused to participate in Thursday’s national moment of silence for the victims of the terror attacks. One teacher said up to 80 percent of his students didn’t want to observe the silence, and some said they supported the attackers. “You reap what you sow,” a student who refused the moment of silence told his teacher in reference to the terrorists’ victims, according to Le Figaro.

Sevran is one of the many notorious banlieues just outside Paris that are home largely to second- and third-generation immigrants from former French colonies in North and West Africa. The town is studded with cement and brick public housing, mostly built in the 1960s and ’70s. Unemployment rates are as high as 35 to 40 percent. Sevran often is lumped in with places like Saint-Denis and nearby Clichy-sous-Bois, the epicenter of weeks of rioting and car burning in 2005. Riots here back in the summer of 1981 led to some of the first mass demonstrations to illustrate the plight of immigrant Algerians, Tunisians, and Moroccans in France.

The 19th arrondissement in Paris has also become synonymous with immigrant frustration and despair after it became known that the Kouachi brothers, Chérif and Saïd, who died in a hail of gunfire last week after killing 12 people, including eight journalists at the Charlie Hebdo satirical magazine, moved there as teenagers and were recruited by a jihadi network. Born in France, the Kouachis were the orphaned sons of Algerian parents.

The popular narrative is that France’s minority populations, specifically those of North African descent, are marginalized and isolated in what are invariably called “gritty,” or “hardscrabble” areas. Shunned by the French majority, reports often say, the children of North African immigrants are frustrated and resentful because they are blocked from traditional routes of advancement.

But many of the Parisian banlieues appear to an outsider much tamer than gun-ridden American ghettoes and bear no resemblance to, say, a typical favela in Rio de Janeiro or the mafia-run Scampia ghetto in Naples. Much of the 19th arrondissement in Paris, where Cherif Kouachi joined the Buttes-Chaumont terror network 10 years ago, looks about as rundown and sketchy today as Brooklyn’s Park Slope.

Indeed at the McDonalds in Sevran, called one of the most dangerous towns in France, the floor is so clean you can almost eat off it and the server actually brings your hamburger and French fries to you in a pristine booth.

“A lot of what you hear about how bad it is here is just not true,” says Pathe Ndiay, 29, whose parents are Senegalese but who was born in France. Ndiay works as a security guard in Sevran and lives nearby. “There’s a lot of unemployment here but not that many young people are out looking for jobs.”

Ndiay said many young men in the banlieues prefer the easy money they can get selling drugs rather than seeking what is likely to be boring, poorly paid employment in Paris.

“They don’t want to be bothered with getting a job,” Ndiay said. “Some can make up to €1,000 to €2,000 a day selling drugs. They want to be rappers. They don’t want to start at some boring job and work their way up the ladder.”

When Boular and his friends were asked if they were looking for work, they said yes. “We try every day,” said one of his friends, who did not want to give his name, but then he started laughing and his friends joined in. They stand in front of McDonalds in Sevran, Boular said, pretty much all day and well into the middle of the night. Boular said he runs home “every now and then” to see his wife and children.

Boular said he recently was released from prison after a two-year sentence for involvement with a car theft. He says he was beaten by guards frequently because he was an Arab. Boular said he and his friends are “blocked” from advancing in French society because they are Arabs and added that his only dream is to “go to Miami and be a rapper and drive a jet-ski.”

A cross-section of young men interviewed in several suburbs last week, including Sevran, Saint-Denis, and Paris’s 19th arrondissement, all spoke of being devout Muslims. None said they supported the Kouachi brothers or their associate Ahmed Coulibaly, who killed four hostages at a kosher supermarket in Paris on Friday, although they all believed the cartoonists at the Charlie Hebdo satirical magazine did not have the right to caricature the prophet Muhammad.

Many spoke out against Israel and Jews as well as the United States but did not seem to have much of a grasp of geopolitics nor did they appear to be very religious in the traditional sense of the word.

Another young man of French-Algerian descent interviewed outside a gas station in the Saint-Denis suburb reacted angrily to a reporter’s presence and demanded to know her religion. “The worst thing is to be atheist,” he said.

The man, who gave his named as “Mohamed,” also said he was a devout Muslim but then changed his demeanor and added, grinning, that he was also “a delinquent.” Then he said he was a drug dealer and without prompting, invited the reporter into the (also very clean) gas station to show an array of hashish for sale in broad daylight on a shelf next to the ATM.

He also called the Paris terrorist attacks “un complot,” or conspiracy, and launched into a lengthy explanation of the “magical Jews” behind it. They were not ordinary Jews, he said, but a “hybrid race of shape shifters” who have extraordinary abilities. “They know how to get in everywhere,” he said. “They are master manipulators.”

Mouhanad Khorchide, a professor of Islamic pedagogy at the University of Munster in Germany told The New York Times last week that while he sees many young Muslims identifying more strongly with their religion he considers it a “hollow religiosity.”

“They would say, ‘Islam is really important for me,’ but they had just dealt drugs,” Khorchide said. “They had a Quran in their backpack and said, ‘With the Quran, I am strong.’ But if you asked if they had read it or knew what it contained, they said no.’”

A French-Algerian named Bentaha Tahar, 30, and his friend who gave his name as Alouane, 31, stood outside Danny Hills restaurant in the 19th arrondissement, right across from the Buttes Chaumont park where Cherif Kouachi received early jihadi training from a charismatic janitor from the nearby Addawa mosque. Mothers pushing babies in expensive strollers and joggers of all ages filled the large, green quite beautiful park.

“The Kouachis insulted Islam,” Tahar said. “They had no right to do what they did. It is against our religion. People need to understand that.”

At the same time, the two grew very heated when they spoke of the resentment they said many French Algerians feel about the United States “and the powers behind it.”

“The Americans are very naïve,” Alouane said. “They get all caught up in a story like this but they don’t see what their own government is doing every day, every week, every year. What right do they have to go out and start wars? The answer is they have no right. They’re out to grab money and power and they always have been.”