Muslims in Europe are secretly amassing an arsenal of the deadliest in biological weaponry: the demographic time bomb. The first phase of the Muslim invasion – or should I say reinvasion – of Europe has already begun with the deployment of an expeditionary force of womb-men: a fearsome army of mutant ninja warriors whose function is to go forth and multiply. Their turbo-charged and perhaps even genetically modified uteruses mass produce the deadly biological agent which is currently being stockpiled in Muslim homes across the continent.

And their mission: to create Eurabia – or, better said, since many European Muslims are not Arabs, to turn the EU into the European Umma. Having been driven out of Europe once and unable to reconquer it through force of arms, those crafty and cunning Muslims are back to do it through the Trojan horse of immigration and reproduction.

Some dismiss this demographic time bomb as being far-fetched and as fantastical as Saddam Hussein's non-existent arsenal of WMD, but yet another smoking gun has been found in the Netherlands. Troubling evidence has emerged that Muhammad has become the most popular boy's name in the country's four biggest cities. And a similar situation is emerging in other European urban centres.

In fact, five centuries after the reconquest of Granada, that last Muslim stronghold, Eurabia has established its first de facto capital in Rotterdam.

And when the number of Muhammads and other assorted Mohammedans become a majority over the coming century – as the great Bernard Lewis warned – they will form an army of mujahideen of Talibanesque horror which will subjugate the natives and make them live as second-class dhimmis under sharia law.

As far-fetched conspiracy theories go, the Eurabia myth is one of the most persistent and dangerous of recent years – and the Daily Telegraph fanned the controversy this month with its claims that it had carried out an investigation which revealed that the EU's Muslim population would jump from the current 4-5% to an improbable 20% by 2050.

The six-paragraph article gives no indication of how the projections were arrived at, nor the assumptions upon which they were based. In fact, as the BBC pointed out in a piece debunking a popular YouTube hit on "Muslim Demographics", population projection is an inexact science. It cites, as an example, the projections made in the 1930s that the UK's population would fall to 20 million by the end of the 20th century.

Most projections that foresee a massive increase in Europe's Muslim population are based on certain assumptions which are hard to justify. They assume that recent immigration trends will continue indefinitely for decades to come, but this is unlikely as Europe continuously raises the immigration bar for non-EU citizens, and it is not far-fetched to expect that many European countries may call a halt to immigration or draw their future immigrants from certain more "desirable" countries.

The projections also assume that European Muslims will continue to have a significantly higher fertility rate than the population at large. But evidence suggests that the fertility rates of Muslim women are gradually converging with those of the wider population. And there are signs that the fertility rate among the white population of some European countries, such as France, is recovering.

So, given that the only hard facts we can be sure of is that a small minority of about 4% of the EU's population is Muslim, why is this fear of a coming Eurabia so strong in certain quarters? Many of the biggest proponents of the Muslim demographic time bomb myth are cheerleaders of and apologists for US imperialism in the Middle East, such as Bat Y'eor and Bernard Lewis.

Some Europeans, particularly from conservative and Christian circles and the intolerant wing of liberalism, have fallen for the myth for a variety of reasons. One is the relatively rapid shift in western Europe towards multicultural, multi-ethnic and multi-religious societies in recent decades, which has caused a certain sense of alienation and insecurity, especially for those whose economic security has been undermined by neo-liberal economics and globalisation.

Other reasons are the massive lifestyle and social changes. These have caused distress for traditionalists and people who still identify themselves as Christian: they have seen their religion die a slow death, while Islam seems to go from strength to strength.

Then, there is the plain old fear stoked by the overexposure given to the most intolerant Islamic fringe groups and individuals. Certainly, there are some European Muslims who want to live according to sharia and there is even a lunatic fringe who would like to see Europe incorporated into some fantastical global caliphate.

But Muslims in Europe are not some unified, monolithic force. Not only are they ethnically diverse and from communities that are not the greatest fans of each other – consider the animosity between Moroccans and Algerians, for example – they are also as varied ideologically as the rest of the population.

Although Muslims tend to be more religious and conservative than the rest of society, there are also plenty of secular, non-practising, cultural and even non-believing Muslims. In addition, it is impossible to tell what kind of identities future European Muslims will have, but I suspect that the future cultural fault lines in Europe will not run along traditional religious lines, but will pit believers against non-believers, creating a kind unity of purpose between conservative Muslims and Christians intent on preserving faith in a "Godless Europe".

While Eurabia is a fantasy, Europe is almost certainly going to become more diverse in the future, and so a debate is worth having about how to adapt to this reality and what constitutes citizenship in an increasingly mobile world.