I'm not overly familiar with Houellebecq, TBH. Some consider him a literary genius, others view him as overrated, shallow and gratuitously provocative (he's one of those leftist intellectuals who dropped Hollande for Macron, yet tends to have the characters of his books express some pretty controversal positions which contribute to blur the lines). Like Michel Onfray (who, while critical of his writing style, praised him as a "mirror of nihilism"), he's also a resolute atheist and has had some harsh words against Islam as a "dangerous religion, thankfully doomed from being undermined by capitalism" in the wake of 9/11.
IIRC, the book you're talking about had been pretty controversal back when it was released, but said controversy was quickly overshadowed by the Charlie-Hebdo
attack, after which he stopped its promotion (ironically, the issue of Charlie
published the day of the attack dedicated its cover to him
* and also contained a rather glowing review in which Bernard Maris, a good friend of his who counted among the victims, praised his book as a masterpiece and denied the accusations of islamophobia against it).
*Translation: "The predictions of Magus Houellebecq: 'In 2015, I'll lose my teeth… In 2022, I'll do Ramadan.'"
Other bit of dramatic irony: cartoonist Luz, who drew this cover, had his 43rd birthday that very same day, and because of that was late to the editorial meeting where the carnage occured, only to cross the path of the terrorists on their way out, where they thankfully failed to recognize him.