As it became clear that the immigrants were not going “home” and that a new Europe with a new kind of citizen was being created, resentments against Muslims bubbled over. This was perhaps the natural outcome of what political philosopher Seyla Benhabib has called the “disaggregation of citizenship” whereby the political rights of citizenship are separated from national belonging.

If a nation is defined as a community where people are linked by shared languages, historical memories, common ancestry and attachment to a certain land, then Europe’s new immigrants were not part of the nations of which they found themselves becoming citizens.

The new Muslim presence provoked amongst some Europeans feelings of alienation within their own countries.

There were those who were embittered by having to share citizenship rights with people who they perceived as irredeemably different. Not only were Muslims “foreign”, they were also seen as welfare spongers living off “real” European taxpayers’ money. Their apparent refusal to integrate into “European” culture was offered as proof of the catastrophic consequences of having opened the Pandora’s box of immigration.

Much antipathy stemmed from Muslim demands that European countries change some of their laws and customs to accommodate their religion. Over the years, Muslim groups had lobbied for and often succeeded in asking for provisions for halal meat in schools, prayer rooms in office buildings, exemption for girls from swimming classes and so on.

The idea that Muslims are all about insisting that Europe accommodate itself to them while steadfastly refusing to accommodate themselves to Europe meant that it had become quite respectable to voice concerns over Europe’s Muslim “problem”. Christopher Caldwell was described by a reviewer in the traditionally left-wing newspaper The Observer (The Guardian’s Sunday edition) as a “bracing clear-eyed analyst of European pieties”. And Caldwell was merely following a path well trodden by a growing tribe of, variably credible but collectively significant, Eurabia exponents.

The Eurabia thesis, in a nutshell, predicts the takeover of an “effeminate” and weak Europe plagued by wrong-headed notions of colonial guilt and misplaced liberalism, by a resurgent and “masculine” Islam.

Immigration in this interpretation is a Trojan Horse via which Muslims infiltrate Europe in order to prepare for an eventual conquest of the continent. It predicts a Europe ruled by sharia law with a Muslim majority population within a few decades, unless exceptional steps – including a rediscovery of Christian belief – are taken to avert this outcome.

Much of the Eurabia line of reasoning is based on demographics. Never mind that Muslims are merely 4 per cent of the EU’s population. For Eurabia proponents, the purported high birth rates amongst Muslim women combined with the low birth rate of “native” Europeans means that it’s only a matter of time before Europe is overrun by the multitudinous progeny of Muslims.

There is, in fact, much data to prove such scaremongering wrong. Across Europe, the birth rates of Muslims are falling, to approach national averages. For example, at last count, Algerian women living in France averaged 2.57 children, higher than the “native” French rate of 1.9, but a significant decrease from the average of seven children they had in the 1970s.

But I could also see why some in Europe might buy a version of the argument. In Revolutions, Caldwell provides lots of seemingly dramatic facts. Britain’s far-right leader Enoch Powell (of “rivers of blood” notoriety), for instance, had predicted that the non-white population of Britain, barely over a million in the late 1960s, would be 4.5 million by 2002.

This figure was dismissed at the time as laughably high. But, in fact, Britain’s ethnic minority population numbered 4.6 million by 2001. The number of white British people in the capital of London fell by 620,000 over the first decade of the new millennium, equivalent to the entire population of Glasgow moving out. As a consequence, white Britons are now in a minority in London, making up just 45 per cent of its residents.

And in some European cities, the possibility of a Muslim-majority population is also no longer quite so ludicrous.

One-third of newborns in Brussels, for example, are of Muslim origin, although currently Muslims make up only 25 per cent of the city population. A third of all children in Paris are born to foreign (although not necessarily Muslim) mothers.

Islam is a very sensory presence in these cities. It’s possible to walk through extensive neighbourhoods where the scent emanating from boulangeries is the sticky-sweet ittar of baklava rather than the warm, flour-dusted aroma of freshly baked baguettes; the posters on the windows of travel agents scream discounts to Morocco and Tunisia rather than Venice or the Costa del Sol; and the snatches of chatter from TV sets permanently hooked up to satellite TV are guttural and unfamiliar.

These are also usually the poorest, most marginalised quarters of a city. On the whole, Europe’s Muslims are a dejected lot who must constantly fight unemployment and discrimination. Yet the idea that they are somehow politically potent, prospective conquerors of the continent is fed by the comparatively greater religiosity of these immigrant communities in relation to the majority population of the host countries.

Islam mobilises more people in Brussels than the church, labour movement or political parties, is what I read in newspapers that carried stories based on the Catholic University of Leuven’s Professor Felice Dassetto’s 2011 work, The Iris and the Crescent. This “mobilisation” ostensibly happens via the city’s seventy-seven mosques and other cultural associations like bookshops.

I met Dr Dassetto one February morning in a French-language bookshop in central Brussels, and found myself wondering whether all the people browsing the bookshelves that day could in any meaningful sense be considered to have been mobilised to a cause or an ideology by their presence in the shop.

Islam was apparently second only to football in its capacity to “mobilise” people in the city.

These categories puzzled me: football, Islam, the labour movement, political parties. They hardly seemed equivalent or exclusive. Couldn’t you be a Muslim trade unionist with a passion for football?

Trying to classify humans on the basis of an isolated, singular identity rather than investigating the messy mesh of identities that constituted the lived reality of most people did not seem particularly helpful. And yet, it is the constant lot of immigrants from Islamic countries to be itemised as Muslims regardless of whether they are fanatics, devout, nominally observant or merely culturally affiliated to the religion. As the Financial Times’ Simon Kuper puts it, there is a danger of seeing “Islam as a bacillus that even secular former Muslims carry around, forever dangerous”.

Professor Dassetto was careful to stress his distance from Eurabia mongers. He was not approving of how some of his data had been used by the media. Of Brussels’ 300,000 “Muslims”, he said, only half were believers in the sense of attending mosques. Why then had they been categorised as Muslims by him, I wondered, but Dassetto was keen to make another point.

The neatly dressed, balding professor, himself a long-term Italian immigrant to Belgium, was keen that Europe did not “stick its head in the sand”. In our postcolonial cities, he said, “religion was now a visible presence in public space”. Given that “Catholicism” had become invisible over time, this reinsertion of religion into secular Europe was “traumatic”.

But Europe is not as secular as it likes to claim.

Religion is not so much absent from the public sphere as much as blended into the cultural background, and so rendered somewhat indiscernible. Virtually all the public holidays in Belgium are Christian ones. Not only Christmas and Easter but also a battery of others, including Ascension Day (when the resurrected Jesus is taken up to heaven), Whit Monday (the day of feasting following Pentecost—when the Holy Spirit descended on Jesus’ disciples) and Assumption Day (when the Virgin Mary made it to heaven). Around half of all schools in Belgium are still denominated as “Catholic”, as are a large number of hospitals.

Nonetheless, the kind of overt religiosity that had been a palpable part of the texture of European life only a few decades ago has indeed been extirpated. Consequently, the traditional Belgian mentalities described by Luc Sante in my dog-eared copy of Factory of Facts fitted immigrants from Morocco’s Rif valley or Turkey’s Anatolian interior far better than it did the contemporary “natives”. If transported to modern-day Europe, Sante’s grandmother would probably have a lot more in common with the waddling, headscarved matrons of Brussels’s immigrant neighbourhoods than with her grandson and his contemporaries.

Excerpted with permission from Punjabi Parmesan: Dispatches from a Europe in Crisis, Pallavi Aiyar, Hamish Hamilton.