Michel Houellebecq’s novel Soumission made its entry into the world under conditions that can confidently be declared unprecedented. Soumission did not simply come out on 7 January, the day when jihadists attacked the offices of Charlie Hebdo; it was both pebble and ripple on a fathomless day.

Breakfast had seen the critics taking chunks out of this preposterous fantasy in which France comes under Islamic rule eight years from now. “Irresponsible,” pronounced Pierre Assouline, a Goncourt jurist; the commentator Patrick Cohen accused Houellebecq of peddling fears and phantasms. To no one’s surprise a caricature of the author was on the cover of the new edition of Charlie Hebdo (“in 2015 I lose my teeth. In 2022, I will do Ramadan”), while Houellebecq himself, bored, saturnine, dentally lamentable, did the rounds of the morning radio and TV shows. After the attacks at 11.30am things got a lot darker and weirder. A faked “extract” from Soumission, purporting to show that it had predicted the attacks, went viral, Houellebecq cancelled further publicity and left town, and, over the next few days, as republican France roared back at the Islamists, Soumission leaped to the top of the bestseller lists – where it remains (it had sold 120,000 copies after only five days).

Soumission marks one of those exceptional instances when politics and art arrive simultaneously. The issues that Houellebecq addresses will define the country in the coming years. Is the birthplace of the Enlightenment foundering under a dangerous multiculturalism? Will the distrust that exists between the republican establishment and many Muslim citizens escalate into open conflict, one consequence being that the dribble of French Jews to Israel grows first into a stream, then a flood? Above all, is there any reason to care passionately either way, or should we sit back, espouse Houellebecq’s preferred compound of spite and phlegm, and welcome these eventualities as the merited deserts of a defunct system?

Soumission marks one of those exceptional instances when politics and art arrive simultaneously

Perhaps the biggest wind-up in Soumission is the abject surrender that Houellebecq arranges for the republican old guard, who have divided themselves complacently into the power-alternating organs of the centre right and the centre left. “France existed before the republic and may exist beyond it,” he told Cohen on the morning of the attacks; the republic is “not a transcendent absolute”. This may seem like an unwise assessment in the light of the je suis Charlie campaign, but it is likely that as unity weakens and the political elites go back to their reptilian ways, Houellebecq’s question will ask itself again: does the republic deserve to save itself?

Houellebecq is France’s best-known writer internationally, his stock-in-trade being satires on various distortions in contemporary life seen through bibulous, chauvinistic, highly sexed men – men like François, the Sorbonne literature professor whose flirtation with the new Islamic regime is the main narrative thread in Soumission. Some in France regard Houellebecq as a traitor, a former tax exile who – since 2005, when French voters rejected a European constitution that its politicians have since promulgated by other means – has refused to vote. Certainly, there is no one in Soumission who shows any sign of wanting to defend republican values such as secularism or equal rights, with the exception of François’s Jewish girlfriend Maryam, who ends up emigrating to Israel – and she lives on in the imagination of her ex-lover less for the integrity of her views than the excellence of her fellatio.

In order to take his mind off things, Houellebecq’s protagonist has frequent recourse to such “specialities of the house” – as the historian Emmanuel Carrère put it in his review in Le Monde. “I helped myself to another large glass of Cahors” is a not untypical line in Soumission. Nor is, “A few days later I met Babeth the Slut …”.

In a scenario that the author regards as entirely plausible – if a bit premature – the France depicted in Soumission is a nation increasingly polarised between the National Front and a recently formed party aimed at representing French Muslims. This is the Muslim Fraternity led by Mohammed Ben Abbes, a debonair, second-generation Frenchman who comes second – behind Marine Le Pen – in the 2022 presidential election (with 22% of the vote, the majority of which must be non-Muslim, an anomaly that Houellebecq doesn’t explain). Following an interlude of chaos and violence, the country settles with relief into a coalition between Ben Abbes and the “flawlessly stupid” François Bayrou – for Houellebecq the epitome of the republican elite in all its grubby ineptitude.

As prime minister, Bayrou is sedated by the grandeur of office while President Ben Abbes moves slickly on with his project. France is Islamised through education, conversions, the promotion of Muslims to key positions and doses of family values. Ben Abbes initiates an expansion of the European Union that reorients it to the south, incorporating Turkey and much of North Africa in a vision that harks back to Rome, Byzantium and the medieval caliphates.

Facebook Twitter Pinterest A commemoration in Paris for those killed during last month’s attack on Charlie Hebdo. Photograph: Michael Bunel/Corbis

The economy is run according to “distributivism”, a form of property-owning capitalism inspired by GK Chesterton and Hilaire Belloc, while the Saudis and Qataris vie for influence over the Arabs’ new home from home (Houellebecq is silent on what effect this will have on property prices in Knightsbridge). The alliance that Ben Abbes forms with the Pope is vital, of course, for as another of Houellebecq’s cynical, intellectually detached male characters puts it: “The real enemy of the Muslims, what they loathe and fear above all, isn’t Catholicism: it’s secularism, laïcité, atheist materialism.”

As the Ben Abbes agenda advances, Soumission generates an unsettling frisson of dread mixed with sexuality, as François’s burqa-clad students glide through the faculty, “slower and more assured than usual, advancing in threes down the corridors, without shaving the walls, as if already mistresses of the terrain”.

Later on, in a Paris-bound TGV, François finds himself sitting across from an obviously well-connected businessman, an Arab of about 50, “dressed in a long white djellaba and keffiyeh, also white”; two women barely out of adolescence and wearing long robes and multicoloured veils – “no doubt his wives” – are buried in teen magazines. Before François decides how far to collaborate with the new regime, Houellebecq sends him on a valedictory tour d’horizon of the old France, which is on the verge of being compromised to the point of reinvention. (Rimbaud, for instance, may continue to be taught at the Sorbonne, but only if his conjectured conversion to Islam is presented as a fact.) Seeking refuge from the political convulsions (which have closed the faculty), François heads to the upper reaches of the Dordogne valley, where, quite implausibly, he is cut off from the world (this is 2022) by news blackouts and dodgy internet connections. He ends up in the medieval town of Martel, named after Charles Martel, hammer of the Muslims at Poitiers. Then, above the famous gorge at Rocamadour, while gazing at a medieval statue of the virgin and child, he experiences the unwonted stirrings of a latent Catholicism.

François is now as close as he will ever be to the 19th-century writer on whose work he is the national authority. This is Joris-Karl Huysmans, a contemporary of Zola and Mallarmé whose beliefs ranged between nihilism, satanism and a redemptive, palliative Catholicism (while dying of cancer), and whose writings oscillated accordingly. Huysmans’ almost suicidal ennui parallels François’s depressive troughs; could the earlier writer’s rebirth as a Catholic offer a solution to his own want of satiety? But François’s final test, when he follows Huysmans’s footsteps to the monastery where he stayed, is a failure, and the aureole of the virgin fades for good. “Nietzsche, the canny old slut, had it right,” he concludes with characteristic finesse. “Christianity was at heart a religion for women.”

The atmosphere back in Paris is more macho, with women conspicuous by their absence from faculty events and the new president of the Sorbonne, a Belgian Muslim convert called Robert Rediger, holding court in a magnificent mansion in the fifth arrondissement, where he flatters François, plying him with a superior Meursault and making him feel infinitely “desirable”. Rediger extols the virtues of polygamy (he has just acquired a 15-year-old junior wife, who scampers around in a Hello Kitty T-shirt), and describes the exact moment when he realised Europe had “accomplished its suicide”. For Rediger, this came with the gratuitous closing of a magnificent art-deco bar in Brussels; and François is prompted to think of a history book about bordellos that alluded to sexual manoeuvres whose names meant nothing to him, and have, like certain artisanal skills, disappeared entirely from the continent’s culture. “How, then,” he asks, “can one resist the idea of the decadence of Europe?”

Houellebecq’s plot seems totally unrealisable, and yet there is truth in his moral tableau

This is an impious preamble to a scene of Muslim conversion. Houellebecq’s position, as on so much else, remains ambiguous. Having undertaken what he describes in interviews as a “deep” reading of the Qur’an, he has concluded that the culture suggested by Islam is something that the west can “negotiate” with. He finds the Ben Abbes regime more “acceptable” than that of the Nazis in the second world war (and why not? It came to power democratically and has embarked on no genocide). But the collaborators who appear in Soumission, François in particular, are prepared to entertain a complete reconsideration of the values – particularly equality between the sexes and the inviolability of adolescence – on which so much of modern western morality rests. For all his rejection of Catholicism and contempt for Europe’s decline, the clincher for François when considering conversion is sex. He wants more of it and this is what polygamy offers. He also wants his job back.

Here, from Europe’s premier literary misanthrope, is an enthralling, stunningly pessimistic view of human nature, which argues that when ideologies are being weighed it is the perks that tip the scales. Of the je suis Charlie spirit there is no sign – the women under Ben Abbes, we assume, have returned docilely to hearth and home.

Houellebecq’s plot seems totally unrealisable, and yet there is truth in his moral tableau. Notwithstanding the heroic Muslim historiography about Islam’s lightning expansion in its early centuries, for the ancient world conversion must have been a cold question of risk and return, as Zoroastrians, Christians, Jews and Manicheans found perfectly sound reasons (tax exemptions, employment possibilities under arms) to submit to the new religion. Why should now – or 2022 – be different?

By tapping into the historic bogey of a Muslim Europe, Soumission revives Edward Gibbon’s famous shiver in The Decline and Fall of the Roman Empire, when he reminded his readers that were it not for the defeat of the caliphal army at Poitiers in 732, “the interpretation of the Qur’an would now be taught in the schools of Oxford, and her pulpits might demonstrate to a circumcised people the sanctity and truth of the revelation of Muhammad”. But things have moved on since the Enlightenment historian. Islam has entered Europe as Christianity once did, becoming authentically and inextricably European in the process. France is in one of its terminal historical crises, with a spate of fin de civilisation jeremiads also claiming the attention of the book-reading public. The sense of history’s cycles, rolling unopposably, is not the monopoly of Michel Houellebecq.

• Soumission is published by Flammarion (€21).