I stopped at the photograph longer than I expected.

The stained glass was still there. High arches rose above the floor. Yet where rows of worshippers once sat, exercise machines now stood beneath the old church ceiling.

People come here to work on their bodies in a building where earlier generations came to think about their souls.

The building is the Sint-Gertrudiskerk in Utrecht, the Netherlands. Built in the 1920s as a Roman Catholic church, it held its last Mass in 2018. Finding another owner for such a large building was not easy. A buyer eventually emerged, and the former church became a health club.

The transformation is real. But the gym is not really the story.

The empty church that came before it is.

Empty Pews Came First

It is easy to look at a photograph like this and declare the spiritual death of Europe. Reality is more complicated.

The Dutch numbers still tell a remarkable story.

In 2010, 55 percent of people aged 15 and older in the Netherlands said they belonged to a religion or religious group. By 2025, the figure had fallen to 42 percent.

Roman Catholic identification fell particularly sharply, from 27 percent to 16 percent during those fifteen years. Protestant identification declined from 18 percent to 12 percent.

Meanwhile, the share reporting no religious affiliation rose from 45 percent to 58 percent.

This change did not happen overnight.

Nor did somebody convert a thriving church into a gym.

The congregation disappeared first.

The exercise machines arrived later.

The Decline Has Much Deeper Roots

European secularisation has no single explanation.

The expansion of the postwar welfare state changed one part of the relationship between citizens and religious institutions. Churches had long played important roles in charity and education. Modern states assumed many functions that religious organisations had once helped provide.

But that cannot explain the scale of secularisation by itself.

Over several generations, organised Christianity also lost influence over everyday life. Religious identity became less automatic. Younger Europeans increasingly inherited churches as part of their cultural landscape without necessarily inheriting the beliefs that built them.

The Netherlands offers an unusually visible example.

The country’s Cultural Heritage Agency says the declining number of active religious people has placed many churches and monasteries under pressure. Some buildings close for worship and acquire another purpose. Others face prolonged vacancy or even demolition.

The Sint-Gertrudiskerk belongs to that larger story.

Its conversion did not cause religious decline.

Religious decline created the conditions for its conversion.

A Gym Makes the Change Impossible to Miss

There is something unusually striking about exercise equipment inside a church.

A library would create a different impression. Apartments might barely attract attention.

A gym produces an immediate visual collision.

A building constructed around salvation now houses a business devoted to physical self-improvement.

I do not say that critically. Looking after one’s health is hardly evidence of moral decline. Nor does declining church attendance prove that people have stopped searching for meaning.

What interests me is the change in purpose.

The original church existed because a community believed something deserved permanence. People financed a large building whose life they expected to extend far beyond their own.

They were right about the building.

The institution inside it proved less permanent.

Why Immigration Enters the Argument

This is where the photograph becomes politically sensitive.

Across Europe, the decline of Christianity now overlaps with another visible development: Muslim communities have become an established part of many European cities.

Put an empty church beside a functioning mosque and an obvious political narrative appears. Christianity is disappearing. Islam is replacing it.

The chronology is more complicated.

In the Netherlands, 45 percent of people aged 15 and older already reported no religious affiliation in 2010. By 2025, the figure had risen to 58 percent.

During the same period, the share identifying as Muslim moved from 5 percent to 6 percent, with some variation between individual years.

The larger European picture points in a similar direction.

Research by the Pew Research Center found that between 2010 and 2020 the biggest driver of religious change in Europe was disaffiliation. Many people raised as Christians stopped identifying as Christian. Europe’s Muslim population also grew, but by far less as a share of the total population than the religiously unaffiliated population did.

Migration therefore matters to Europe’s religious landscape. It does not provide a sufficient explanation for Christian decline.

Muslims did not empty the pews of the Sint-Gertrudiskerk.

Fewer Dutch Christians filled them.

That distinction matters because Europe’s arguments about religion increasingly overlap with arguments about immigration and national identity.

A society can misdiagnose its present when it misunderstands the chronology of its own change.

But Perhaps the Gym Saved the Church

I initially saw the photograph as a story about loss.

There is another way to read it.

What would have happened to the Sint-Gertrudiskerk without a new owner?

The Dutch Cultural Heritage Agency actively encourages adaptive reuse of vacant historic buildings. Religious properties are particularly vulnerable because maintaining large structures becomes difficult once their original users disappear.

Reuse can prevent a building from standing empty until deterioration makes preservation impossible.

That changes the meaning of the photograph.

The gym may not represent the destruction of the church building at all. It may be one reason the building survived.

The conversion retained important elements of the old structure. Its architecture remains visible, and the church bells have even been rung again.

There is something rather Dutch about the solution. A building loses its original function, yet instead of allowing it to decay, people search for another use.

Practical. Economical.

But it creates another question.

What exactly has been preserved?

The Netherlands Is Not the Whole of Europe

One Dutch church cannot explain a continent.

Europe’s religious landscape remains highly uneven. Poland is not the Netherlands. Italy has its own history, while Germany contains substantial regional differences inherited from both the Reformation and the division between East and West.

Even within Western Europe, Christian identity has not simply disappeared.

Pew Research Center found that many Western Europeans continued to identify as Christian despite attending church rarely. Christianity can therefore survive as cultural identity after regular religious practice declines.

That distinction has become politically important.

A person may seldom enter a church yet still regard Christianity as part of national history. Once immigration enters the debate, cultural Christianity can acquire new importance even among people who are not particularly religious.

Germany illustrates why this question matters beyond the Netherlands.

Arguments about Islam, migration and national identity frequently intersect with questions about what constitutes European culture. Yet describing Europe as historically Christian is not the same as demonstrating that contemporary Europeans remain practising Christians.

The difference between those two ideas is becoming harder to ignore.

An empty church makes it visible.

Preserving the Stone, Losing the Story

Europe has become remarkably good at preserving heritage after the original purpose of that heritage has weakened.

Old churches attract visitors who may never attend a religious service. Governments protect religious monuments because citizens value their architecture and history even when fewer people accept the theology that produced them.

Perhaps there is nothing unusual about this.

Civilisations constantly reuse inherited buildings. Structures outlive the institutions that created them.

Religious architecture creates a special difficulty, though.

Its meaning was never entirely architectural.

Someone raised those arches because a community believed certain things deserved permanence. Remove that belief and the physical object can survive while its meaning changes.

The Sint-Gertrudiskerk captures that tension.

The bricks survived secularisation.

The purpose changed.

Can Secular Europe Supply Its Own Meaning?

A secular society is not necessarily a society without values.

European democracies continue to organize themselves around constitutional government and individual liberty. Human rights remain embedded in European institutions.

There is also no simple historical answer to where those principles came from.

Christianity forms part of Europe’s intellectual inheritance. So do traditions that challenged church authority. Modern European institutions also grew from the political lessons drawn after the continent’s twentieth-century catastrophes.

The more interesting question concerns what happens next.

Can societies maintain strong obligations between citizens when fewer people share the religious framework that once helped explain those obligations?

Perhaps they can.

The Netherlands itself provides an important warning against easy claims of social collapse. Dutch secularisation has advanced dramatically, yet recent official statistics show relatively high levels of interpersonal trust. Losing religious affiliation therefore does not automatically produce civic breakdown.

That complicates the church photograph, and it should.

The image cannot prove that secular Europe has failed.

It can show us how profoundly Europe has changed.

I Looked at the Photograph Again

After looking at the Dutch numbers, I returned to the image.

The exercise machines seemed less important this time.

My eyes moved upward toward the arches and stained glass surrounding them.

Someone once built that church because a community believed its purpose would endure. A century later, another generation looked at the same building and found another use for it.

Perhaps adaptive reuse is simply what sensible societies do with buildings they no longer need for their original purpose.

In Utrecht, it may have helped save a remarkable piece of architecture.

The stone survived.

The story changed.

And that leaves me with the question I cannot get out of the photograph:

When a civilisation preserves the monument but no longer shares the conviction that built it, what exactly has it preserved?

Editor’s note: An earlier version of this essay appeared on Munaeem.org. This edition has been substantially revised and expanded for Munaeem.de with updated data, additional sourcing and a broader examination of religious change in Europe.