French Muslims disgusted by the shootings in Paris may nonetheless have reasons for not embracing the slogan "I am Charlie".
"For a Muslim, the Prophet Muhammad is more important than their own parents," says the young man I meet in Sarcelles, his face twisted with contempt for the caricatures Charlie Hebdo published.
His friend, also 18, nods in agreement as we stand on a street in this Paris dormitory town, famous in France for its large Sephardic Jewish community.
"They were warned but they kept on mocking the prophet," he continues. "But you cannot kill for that. You cannot go against press freedom in France. Still, they will have to answer to God."
"Real Muslims condemn these attacks," adds a third man, 22 and also Muslim. "Those who committed them were insane. The attack on the kosher supermarket was a catastrophe for France and for the world. If you kill one man it is like you kill all of humanity. That is how we think."
We stand chatting openly on the pavement but nobody wants to be identified.
Mistrust of the media runs deep since an outburst of violence last July when police held rioters back from entering the town's Jewish area as they raged at Israel's bombardment of Gaza.
An invisible line marks the beginning of the Jewish area on Avenue Paul Valery, scene of the confrontation with the police. It starts just before a Holocaust monument and a synagogue.
There is no sign of trouble but it has been guarded by CRS riot police since last week.
David, a kosher businessman I encounter, is so dismayed by the deterioration he perceives in community relations in France that he foresees a time when the "great majority" of its half-million or so Jews will emigrate.
But the Muslim teenager accuses French media of exaggerating the divisions in Sarcelles, where Jews now make up about a quarter of the 60,000-strong population. "We say one thing, you might write another," he suggests, smiling.
When I ask how he and his friends relate to the town's Jewish community, they say they have Jewish friends and "nothing has changed". "Mosques get attacked but that doesn't make the news," he adds.
The older of the three speaks with real warmth of the French values of liberty, equality and fraternity which were schooled into him.
"When I go on holiday to Morocco, I know I could never live there because people make me feel French," he says of his ancestral country. "But in France I am made to feel Moroccan," he adds.
"Am I going up to the Jewish area?" asks the younger man. The Jews got the nice part of Sarcelles, he explains, a little sourly, while we got this, gesturing back to the long blocks of uniform five-storey council flats stretching down to the railway station.
Actually, there was a time when Jewish immigrants from the former French colonies lived there themselves in numbers, and some Jews still do, but the demographic has changed.
By the mosque near the station, old men sit and chat in Arabic.
A Tunisian Muslim pensioner I meet gives two reasons why he shunned Sunday's national unity march in Paris, while condemning the attacks.
Like the teenagers, he is indignant at the cartoons Charlie Hebdo published: "It set out to provoke people for its own amusement.
"It attacked their religion. Make fun of yourselves if you will, but leave others alone. The media is like a car: you need to have a licence to be on the road, otherwise you will be a danger to others. Charlie had no licence to put people's lives at risk with their provocations."
His other reason is the presence at the march of Israeli Prime Minister Benjamin Netanyahu whom he calls "the biggest terrorist in the world" because of the Gaza conflict.
He insists he is not anti-Jewish, saying he had Jewish friends back in Tunisia.
Another Muslim pensioner I meet separately, a man from Morocco, says he has Jewish friends too, here in France, men he will "have a coffee or beer with".
He takes a rather detached view of Charlie Hebdo, dismissing it as a fringe paper he never wanted to read. "But I am 200% in support of freedom of expression," he declares.
More Muslims might have attended the march had they not felt "shame", he suggests, at the actions of gunmen claiming to defend Islam. "Muslims may also fear retaliation by jihadists if they take to the streets," he adds.
He himself is uneasy after the attacks. "Nobody is safe now," he says before directing me to the nearest tram stop.
As my tram glides out of Sarcelles, I reflect that I have not seen a single "I am Charlie" poster or pencil symbol since my arrival yet the quiet battle of ideas here is no less intense than in Paris itself.