‘Something has changed!” That phrase dominated conversation, including the media, in much of France a day after the worst carnage the country has experienced in peacetime.

Some labeled the attack in the heart of Paris, in which Islamist terrorists assassinated 12 people including five prominent journalists, as “our 9/11.”

At first glance, it did seem something had changed.

Hours after the attack on Wednesday and throughout the next day, France saw hundreds of marches and gatherings, including some in small towns and villages, to show solidarity with the victims of the attack and voice support for press freedom and democratic rights. Posters and buttons with the slogan “Je Suis Charlie” (“I Am Charlie”) showing support for the satiric weekly Charlie Hebdo, sold like hot cakes and adorned shop windows, walls and clothes.

President Francois Hollande called a national day of mourning, with a minute of silence observed nationwide by church bells chiming across the land. This was the fifth time in the history of the Fifth Republic that France observed a day of national mourning; the last, on Sept. 14, 2001, marked the 9/11 attacks on the United States.

There were other symbolic gestures. Christian and Jewish leaders visited the main mosque in Paris to pray with its imam. Scores of associations issued messages of sympathy for the victims and their families.

On closer examination, however, there was little sign that a genuine debate on the roots of the tragedy might start anytime soon. Whenever the discussion edged close to the core of the issue, the usual suspects of multiculturalism and political correctness intervened to put it on a different trajectory.

It seemed almost mandatory to assert that the attack, carried out by a three-man commando of French-born jihadists of Algerian origin, had nothing to do with Islam. The obvious question went unasked: If so, then why did the president and prime minister — indeed the whole political elite — keep reassuring the “Muslim community?”

The self-styled spokesmen for ­Islam, including a string of imams in a variety of folkloric garbs, played the same comedy by insisting that the three jihadists represented only themselves and that Islam is a religion of love and peace.

On the “love and peace” note, it’s remarkable that none of the “community leaders” and “spokesmen” was prepared to ­label the three murderers as ­jihadists or even terrorists, let alone “enemies of mankind.”

Instead, echoing President Obama, they all described the killing squad as “violent extremists.” Even Hassan Chalghoumi, a Tunisian-born cleric regarded as France’s “most moderate imam,” would go no further than describing the killers as “misguided individuals.”

Some “Muslim spokesmen” tried to spin a web of confusion by using words and phrases many French adore — “alternative narratives,” “ historic concepts,” “discourse.” They recalled France’s 100-year colonial presence in Algeria, though the Charlie Hebdo attackers had never been to Algeria and made it clear they were seeking revenge for the Prophet.

In a Europe 1 Radio interview, Tariq Ramadan, a former adviser on Islam to the government, even insisted that the attack should remind the French that all lives are of equal value, including those lost by Muslims in Syria and Iraq. In other words, if France takes part in the fight against ISIS, it must expect attacks on its citizens.

Non-Muslim talking heads, meanwhile, warned against racism and Islamophobia, praised religious tolerance and dwelt on the merits of multiculturalism and alterite (otherness) for all communities. Leftist commentators tried to inject a dose of class warfare into the debate by harping on the poverty in heavily Muslim neighborhoods.

All of this demonstrates the confusion that grips France with regard to Muslims, now almost 10 percent of its population.

First, there is no “Muslim community.” French Muslims are divided into numerous different sects and “ways,” with little or no organic contact among them.

In the Rochechouart neighborhood of Paris, you find mosques within a few hundred yards of each other that attract believers on the basis only of nationality; Algerians shun the Moroccan mosque, and vice versa. In fact, France allows ­rival Muslim sects, people who would kill one another in any Muslim country, the rare opportunity of peaceful coexistence.

Nor is Islam a race. Walk in a Paris street and you’ll likely run into Muslims from all races.

Islam cannot be regarded as an ethnicity, either, as more than 50 countries across the globe have Muslim majorities. And at least a fifth of France’s Muslim citizens are long-established Frenchies who converted to Islam.

Nor is Islam a “class,” let alone an underclass or neoproletariat, as leftist star Jean-Luc Melanchon claims. There are many super-rich individuals and families among French Muslims.

And, for a while, it was fashionable for the French glitterati to convert to Islam (the mystical Sufi version, of course) to thumb their noses at the “materialist civilization” of the West.

This, in fact, is partly the subject of Michel Houellebecq’s latest novel “Submission,” which was on the cover of Charlie Hebdo’s issue the day its editorial office was attacked. The “hero” of “Submission” is a university teacher who ends up converting to Islam after the election of an Obama-like character as France’s new president in 2022.

The multiculturalist position on Islam is equally open to question — because Islam is not a culture. Ask an Algerian if his culture has anything in common with a fellow Muslim from Nigeria, and you’ll be laughed out of the room.

Neither a community, nor a race, nor yet a culture, an ethnicity or social class, Islam can and must be regarded as what it claims to be: a religion.

Yet, as such, it should behave as a religion. That is to say: develop a theology, some sense of transcendence and a moral structure to advocate and defend a set of beliefs. However, this is precisely what modern Islam is not, perhaps does not want to be.

Unable to perform as a religion, modern Islam (in most of its varieties) acts like a political movement. It is obsessed with jihad and martyrdom, Kashmir, Palestine, world conquest, hijab, beards, uniforms and other paraphernalia of totalitarianism.

In many mosques, including some in France, God is given no more than a cameo role, as jihadists, suicide bombers, hostage-takers and ISIS-style throat-cutters get top billing.

On Thursday, Iran’s minister of Islamic guidance, Ali Jannati implicitly justified the murder of Charlie Hebdo staff: “Press freedom can’t justify insulting religion,” he said. Foreign Ministry spokeswoman Marzieh Afkham went further: “Freedom of expression should not include disparaging what is sacred.”

Meanwhile, the British group “Love Muhammad” announced plans to expand its operation to the rest of Europe to “unite Sunni and Shia in a common love of Our Beloved Messenger.”

The real problem is that Islam, refusing to do the job of a religion and acting as a political movement is simultaneously demanding the deference that was once, in pre-democratic times, due to religious beliefs.

If France, indeed Europe, has a problem with Islam, it is partly because Islam has a problem with itself.