Demographics, Immigration and Birth Rates: What Do We Really Know, and What Can We Expect?
We do not know which European cities will have a Muslim majority in 2100. But we can ask which cities are currently following a demographic trajectory that could take them in that direction. And this question is far more interesting than it might seem.
When we talk about the Muslim population in Europe, we tend to look at national figures: France, Germany, the United Kingdom, Belgium, the Netherlands… But Europe is not changing uniformly.
Demographic change is concentrated particularly in certain large cities and urban neighbourhoods.
In some areas of Birmingham, for example, people identifying as Muslim already make up the majority of the population. In 2021, 29.9% of Birmingham’s entire population identified as Muslim, but in some neighbourhoods the proportion exceeded 80%. In Small Heath, it reached 85.9%.
The question, therefore, is not simply: How many Muslims will there be in Europe?
The question is also: Where will they be concentrated? And this is where an issue that Europe is still discussing far too little begins.
First: An Important Clarification
There is no reliable scientific prediction that allows us to say, “In 2100, Birmingham will have a Muslim population of 62%,” or “Brussels will be Muslim in 2085.” That would mean inventing a level of precision that the data cannot support.
Demographic projections over such a long period depend on too many variables: immigration, emigration, birth rates, mortality, changes in religious identity, wars and conflicts, economic conditions, and political decisions that we cannot yet foresee.
Even the Pew Research Center’s projections for Europe extend primarily to 2050 and present different migration scenarios. They are not predictions of what will necessarily happen.
For this reason, discussing 2100 means discussing scenarios, not certainties.
What Do We Know Today?
In 2016, Pew estimated that there were approximately 25.8 million Muslims in Europe, representing around 4.9% of the population.
Under its zero-migration scenario, the proportion would rise to 7.4% by 2050.
Under a medium-migration scenario, it would reach approximately 11.2%.
And under a high-migration scenario, it could reach around 14%.
Why would the proportion increase even if immigration stopped? Mainly for two reasons: a relatively young Muslim population and historically higher birth rates than those of the non-Muslim population.
For the 2015–2020 period, Pew estimated a fertility rate of approximately 2.6 children per Muslim woman, compared with 1.6 among non-Muslim women in Europe. However, the research itself noted that this gap tends to narrow across generations.
And here another fundamental phenomenon emerges: Europe is also becoming increasingly secular.
We are not simply witnessing the growth of Islam. We are seeing two simultaneous developments: less Christianity, a larger Muslim population, and more people with no religious affiliation. This completely changes Europe’s religious landscape.
So, Which Cities Could Be Most Exposed to These Changes?
We cannot produce a scientific ranking of “Muslim cities in 2100”. But we can identify cities that start from particularly significant positions.
1. Birmingham: The Most Obvious Case
Birmingham, in England, is probably the most important example for understanding the possible future of certain European cities.
In 2021, 29.9% of Birmingham’s population identified as Muslim. But the truly striking figures concern particular neighbourhoods. In Small Heath, the proportion reached 85.9%. In Alum Rock, it was 83.7%. In Bordesley Green, 80.2%. In Sparkhill, 79.2%.
This means that a city’s demographic future does not have to unfold uniformly. It can begin in specific neighbourhoods.
First, areas emerge where a population becomes concentrated. Then come commercial networks, restaurants, shops, associations, and mosques. Finally, certain districts may undergo a profound transformation.
Birmingham demonstrates that this phenomenon is not a futuristic theory. It can already be observed today.
2. Brussels: A Particularly Sensitive Case
Brussels is another major European example.
The city and its metropolitan area have a significant population originating from Muslim-majority countries, particularly Morocco and Turkey, as well as communities from the Middle East and other regions.
But there is an important difficulty: Belgium does not have religious statistics comparable to those provided by the British census. Therefore, figures circulating about “the Muslim percentage of Brussels” should be treated with considerable caution.
What we can say is that Brussels combines several factors that may favour the growth of this population: a high urban concentration, international immigration, a young population, considerable diversity, and concentrations of communities of Muslim origin.
Brussels does not need to become a majority-Muslim city to undergo significant transformation. Some neighbourhoods may change considerably before the city as a whole does.
3. Marseille: France’s Great Laboratory
Marseille deserves particular attention.
The city has a long history of immigration from North Africa and a population of Algerian, Moroccan, Tunisian, and other Muslim-majority-country origins.
But another problem arises here: France does not ask about religion in its censuses in the same way as the United Kingdom.
Consequently, there is no precise official percentage of Muslims in Marseille comparable to Birmingham’s 29.9%.
Nevertheless, the territorial concentration of people of North African origin makes Marseille one of the main places to study the future evolution of Islam in Europe.
And here, too, an important distinction must be made: Muslim background does not automatically mean religious practice.
Someone may come from a Muslim family and be minimally religious, agnostic, or atheist.
It would therefore be a mistake to equate foreign origin with being Muslim, or an Arabic surname with being a practising Muslim.
Religious demography is much more complex.
4. Vienna
Vienna is another interesting case.
In 2021, approximately 8.3% of Austria’s population was Muslim. Vienna also concentrates a significant proportion of the country’s immigrant population.
Official city figures show that in 2021 approximately 284,930 people in Vienna declared Islam as their religion, compared with a total population of around 1.92 million. That represents approximately 14.8% of the city’s population.
But an even more important detail is how Vienna’s historical development illustrates the way one religion can grow while another loses ground.
In 2001, Vienna had approximately 121,000 Muslims. By 2021, the number had reached around 285,000. At the same time, the number of people with no religious affiliation stood at approximately 655,000.
Therefore, Vienna’s future will not necessarily follow the pattern Christianity → Islam. It could be much more complex: Christianity → secularisation + Islam + other religions.
5. Amsterdam
Amsterdam presents a different scenario.
In 2024, approximately 9% of Amsterdam’s adult residents identified with Islam. Ten years earlier, the percentage had been higher.
This is a very important finding because it demonstrates that trends do not always move in a straight line. The Muslim population may increase during one period and subsequently stabilise or even decline as a proportion of the total population.
That is why we should not make a mechanical extrapolation such as: 9% today × seven decades = a Muslim majority.
What About Rotterdam, Paris, London or Berlin?
These are also cities worth watching.
London, Paris, Rotterdam, Berlin, Manchester, Leicester, Bradford, Birmingham, Brussels, Vienna, Amsterdam, and Marseille are among Europe’s major urban areas where the Muslim presence is particularly significant.
But they are not all following the same trajectory.
And here we reach a fundamental conclusion: there is no single “Muslim future” for Europe. There are many different demographic futures within Europe.
One city may have 30% Muslims, another 10%, and another 5%. Within each city, some neighbourhoods may have an 80% Muslim population while others have just 2%.
What Would Have to Happen for a City to Become Majority-Muslim?
Having a significant Muslim population is not enough to achieve a Muslim majority.
Several factors would have to combine over many decades.
1. High immigration
A sustained arrival of people from Muslim-majority countries would rapidly increase their demographic weight.
2. Higher birth rates
If the Muslim population maintained a higher fertility rate than the rest of the population for generations, its share would increase.
3. A young population
A young population has more people of childbearing age.
This creates demographic momentum that can persist for decades.
4. Urban concentration
Immigration tends to concentrate in large cities.
This can produce much faster changes locally than at the national level.
5. Secularisation among the rest of the population
This factor is often overlooked.
If Europeans progressively abandon traditional religions, Islam’s relative share may increase even if its absolute growth is not spectacular.
Would It Necessarily Be a Problem if a European City Had a Muslim Majority?
No. The religion of the majority does not automatically determine the democratic quality of a society.
A city can have a Muslim majority and still maintain religious freedom, freedom of expression, equality between men and women, LGBT rights, separation of religion and state, and liberal democracy.
The issue should therefore not be framed as: “How many Muslims can Europe tolerate?”
The right question is: Can Europe uphold its democratic principles regardless of which religion forms the majority?
That is the real debate.
Which Cities Should We Pay Particular Attention To?
If we were to create a “demographic watch map”, I would start with Birmingham, Brussels, Marseille, Vienna, London, Rotterdam, Amsterdam, Paris, Berlin, Manchester, Leicester, and Bradford.
This does not mean that all these cities will have Muslim majorities. It means they are places where the evolution of the Muslim population, immigration, birth rates, secularisation, and territorial concentration deserves to be studied.
Birmingham is currently the most striking case because Muslims already account for almost 30% of the entire municipal population, while exceeding 80% in some districts.
Vienna also demonstrates significant change: approximately 285,000 residents identified as Muslim in 2021, representing around 15% of the city’s population.
Amsterdam, by contrast, shows why linear extrapolations can be misleading: in 2024, 9% of adults identified with Islam, and that proportion was lower than in previous years.
The Potential Risks
Demographic transformation does not have to lead to conflict, but it would also be unrealistic to deny that it can generate tensions.
1. Residential Segregation
If particular groups become concentrated in particular neighbourhoods over generations, a socially divided city may emerge.
Not necessarily because of an official border.
Rather, separation may develop through schools, housing, shops, associations, places of worship, languages, marriages, and personal relationships.
The result may be a city where different groups live physically close to one another but remain socially far apart.
2. Pressure on Equality Between Men and Women
Europe must be particularly clear on this issue.
The problem is not that someone is Muslim. The problem arises when certain religious interpretations conflict with fundamental rights.
Examples include forced marriages, control over clothing, discrimination against women, gender segregation, so-called honour-based violence, and restrictions on personal freedom.
These problems must be challenged regardless of who commits them.
3. Freedom of Expression
Europe has a particularly strong tradition of freedom of expression.
This includes the right to criticise ideologies, religions, churches, mosques, and any other institution.
A democratic society cannot place any religion in a protected zone beyond criticism.
4. The Emergence of Parallel Authorities
Another risk arises when communities create such closed social structures that some people end up living under different informal rules.
The state must prevent the emergence of two systems of citizenship: one based on the law and another based on community pressure.
Religious freedom means being able to practise a religion. It also means being able to leave it. And one right deserves much more attention here: the freedom to stop being Muslim.
5. Radicalisation
A small minority can have an enormous impact if it adopts extremist positions.
6. The Reaction of the Population
There is another danger. When citizens feel that significant changes are taking place without public debate, a political backlash may emerge. That reaction can become more radical than the original problem.
If mainstream parties refuse to discuss immigration, integration, religion, or security, other parties will eventually occupy that space. Silence also has consequences.
The Big Mistake: Thinking There Are Only Two Options
Europe often falls into two extremes.
Option A: “Everything is perfectly fine. There is no problem.”
Option B: “Europe will be conquered by Islam.”
Both oversimplify a much more complicated reality.
The reality will probably be a much more diverse, much more secular Europe, with a considerably larger Muslim presence than today.
But that does not necessarily mean a Europe governed by religion.
So, What Can We Do?
One Common Law for Everyone
The first rule should be very simple: the same law, the same rights, and the same obligations.
Integration, Not Isolation
Integration should not mean: “Abandon your culture.”
But neither should it mean: “Every community can live by its own rules.”
Integration means sharing a common citizenship.
Defend Freedom of Conscience
Europe should protect both the right to believe and the right not to believe. It should also protect the right to change religion.
This last freedom is particularly important in societies where religious identity may be closely linked to family and community.
Create a European Observatory on Islam and Integration
Europe could establish an independent body to study demographics, immigration, integration, secularisation, Islamism, and fundamental rights on an ongoing basis.
Not to monitor Muslims, but to understand what is happening. A serious democracy cannot design public policies based on rumours circulating on social media.
2100: The Real Question
Perhaps, 75 years from now, some European cities will have Muslim majorities. Perhaps they will not. Perhaps some urban areas will reach that majority while their countries remain clearly non-Muslim-majority societies.
But there is something we can decide today. We cannot completely control demographics, but we can decide what kind of society we want to build.
A Europe where everyone can believe.
A Europe where everyone can stop believing.
A Europe where women can dress as they choose.
Where gay people can live freely.
Where people can criticise a religion without fear.
Where nobody stands above the law.
And where no community has greater rights than another.
That should be the real objective.
Because Europe’s future should not depend on whether a city has 20%, 40%, or 60% Muslims in 2100.
It should depend on something much more important: will it still be a society of free and equal citizens?