Turkey’s government looks set to turn the great former church of Hagia Sophia from a museum to a functioning mosque. By way of context, when the building was erected in the 530s, it was by far the world’s largest church, and remained so for nine hundred years. Then it was a vast mosque, and then (from 1934) a secular museum. A great deal has been written about what looks like a major tilt to Islamist causes by Turkey’s populist authoritarian leader, Recep Tayyip Erdoğan,  Yesterday, at Anxious Bench, my colleague John Turner did a terrific piece about this epochal event and its historic meaning. What I would add to all this is a larger social context. In my view, nothing that Erdoğan does or says makes sense except in terms of demographics, and the demographics of religion, and that is emphatically true of the current situation. This is all about faith and fertility, a theme dear to my heart.

Hagia Sophia: photo is in public domain

Many countries are divided between prosperous and progressive communities and poorer, less educated societies, and commonly that divide follows urban/rural lines. Both demography and religion mark critical dividers, which both symbolize and accentuate larger conflicts of class, race, wealth, and ethnicity. Such a situation offers rich rewards for a movement or party to exploit these intermingled causes of faith and fertility, but the actual outcomes vary according to the political situation. Commonly, a party or regime will ally with the numerous and growing high-fertility population against the declining elites—to espouse values of the rising faithful against the shrinking secularists.

If a country practices electoral democracy, that means that a party or movement appealing to those traditional religious values will find a rock-solid political base, a secure bastion against secular liberalism, feminism, and cosmopolitanism. The more the educated and progressive population complains about such policies, the easier it is to stigmatize them as enemies of faith, or of the nation, and that in turn reinforces the loyalty of the poor and excluded, the fertile and faithful. Governments can also pledge to work for higher fertility and more babies, in an attempt to restore national strength and integrity, but such policies also proclaim the superiority of the values of the poor and faithful.

When a country has these two demographic faces, it makes great sense for a populist party to show itself as pious and devout as it can be. Arguably, they would be foolish not to.

Turkey offers an egregious example. Over the past decade, the country’s affairs have been critical to the larger Middle East and have attracted keen interest from the United States, Russia, and Israel, among others. In the 2010s Turkish attitudes and decisions shaped the struggle against the Islamic State and the response to the Syrian civil wars. Any worthwhile attempt to understand those issues must of necessity draw heavily on demographic concerns and the differential demographics of a divided nation.

Since 2002 Turkey has been dominated politically by the Justice and Development Party (AKP). That party is led by Erdoğan, who since 2014 has served as the country’s president. Originally presented as a standard-bearer for a moderate and pragmatic form of Islamism, the party has become steadily more authoritarian. Erdoğan himself has emerged as a charismatic strongman practicing an authoritarian populism. His government appeals to its poorer and more religious citizens by preaching much more conservative versions of the country’s dominant faith, a startling departure from the country’s recent history

That Islamist drift is difficult to comprehend without some knowledge of modern Turkish history. In its modern form, the country emerged in the 1920s from the wreckage of the historic Ottoman Empire. Under the leadership of Mustafa Kemal Atatürk (“Father of the Turks”), the country made a radical leap to modernization, enforced by stern government intervention. Turks were required to forsake traditional clothes for Western dress, and the language was to be written in a Western-style alphabet. The country became aggressively secular in its public life, prohibiting conspicuous signs of religious faith and suppressing the once powerful Sufi orders. In 1934, as I noted, Hagia Sophia became a museum.

While Islamic life was accepted and tolerated, the country’s religious institutions were under the firm hand of a central Presidency of Religious Affairs, the Diyanet. Secularist and Kemalist views were deeply entrenched in the political and military establishment, which struggled to resist the new wave of Islamic politics sweeping much of the region in the late twentieth century. One major flashpoint was women’s use of headscarves, the hijab, which were strictly forbidden in institutions of public education.

Under the AKP, Islamic institutions, newspapers, and media outlets have all flourished. The government has approved the wearing of hijabs in universities and even by women police officers. Erdoğan has openly advocated far-reaching policies of Islamization, including restrictions on alcohol and the prohibition of public displays of suggestive activity, including kissing. His government has actively favored the building or restoration of mosques and of historic Ottoman sites. From a Western perspective, this all falls far short of the atrocities of the Islamic State, but in Turkish terms it is startling enough, even revolutionary.

Recalling the country’s former regime, when the Sultan also claimed to be the Caliph of Islam, critics describe Erdoğan’s rule as “neo-Ottoman.” The recent developments surrounding Hagia Sophia fit this scheme perfectly.

Erdoğan’s promotion of faith can be understood only against the country’s unusual demographic patterns. Overall Turkey’s fertility rate is a little below replacement at 2.0, but that simple fact obscures enormous regional variations. The country can roughly be divided into four zones, stretching from west to east. The western quarter is thoroughly European in demographic terms, with sub-Danish fertility rates of around 1.5. That is not surprising in light of the close ties uniting those regions to Europe, the impact of European media, and the extensive Turkish migration to lands like Germany and the Netherlands. Naturally, many of those migrants brought European ways and attitudes home with them.

But the nation’s other regions exhibit quite different patterns. Fertility rates rise steadily as we travel farther east into Anatolia, until the upland east has very high rates resembling those of neighboring Iraq or Syria. The far-western province of Edirne has a TFR of 1.5, while in the southeast Şanlıurfa is over 4.34. That disparity is far greater than we find between liberal and conservative regions of the United States. Turkey’s median age is 31.5—high by Middle Eastern standards, but again, the rate varies a great deal from west to east, as older westerners confront younger easterners. “Europe” and the Third World – Sterilia and Fertilia – jostle each other within one nation.

As we would expect, that demographic gradation closely tracks expressions of religious zeal. The high-fertility regions of eastern and central Turkey are much more religious than the secular west, and this is where we find the Quran Belt that so regularly supports Islamic and fundamentalist causes. It simply makes electoral sense for the government to respond to the interests of that populous and growing area, and to drift ever more steadily in Islamist directions. In the 2015 elections, the AKP did badly in western and coastal regions with fertility rates well below replacement. Conversely, it won its greatest successes in the high-fertility regions of south-central Turkey, between Konya and Malatya, and in many eastern sections. The very high-fertility region of Şanlıurfa is an AKP fortress. As so often around the world, religious parties find their electoral strongholds in high-fertility areas.

But there is a complicating fact here, which further contributes to the demographic underpinnings of the country’s politics. It may seem odd at first that those triumphs in south-central regions were not wholly replicated farther east in the very high-fertility areas of the far southeast, around cities like Diyarbakir. In fact the AKP met its sturdiest opposition there. But besides the fast-breeding Turks in those eastern regions, we also find members of a significant non-Turkish minority who likewise display extremely high fertility. These are what the Turkish government euphemistically calls the “Mountain Turks” but which are properly known as Kurds. Turkey’s Kurdish minority, usually estimated at around 15 to 20 percent of the population, is expanding rapidly, posing a demographic threat that dominates the thinking and the rhetoric of President Erdoğan.

Throughout his time in office, the president has consistently and repeatedly stressed these demographic themes, to the bafflement or contempt of Western observers, for whom such causes do not resonate in the slightest. Erdoğan has issued apocalyptic warnings that Turkey will possess a national Kurdish majority within just a couple of decades, far earlier than most demographers would predict. Fears of Kurdish growth or domination go far toward explaining why, over the past decade, the Turkish government so often preferred to act militarily against that Kurdish community, rather than against the Islamic State that most Western observers viewed as a critical danger to regional stability and peace. From a Turkish point of view, though, the Islamic State was an irritant, while the Kurds posed an existential demographic threat.

In the face of seemingly imminent demographic catastrophe, Turkey faces limited options. Like many other countries in a similar position, the government can deploy the usual array of incentives to encourage non-Kurdish citizens to start breeding again—even those Western-oriented secularists—and to get the national fertility rate closer to 3.0 than 2.0. As the president has said, “If you have a young population, the future is yours. . . . But when we look at the increase, if we continue like this, alarm bells are ringing for 2037–40.” He has urged Turkish people that “at least three children you must have, before it’s too late,” and further describes abortion as a “plan to wipe the country off the world stage.” He tries to persuade Turkish families living in Europe to have five children, as part of an explicit scheme to promote Turkish and Islamic values. Beyond the usual natalist incentives, the government extols religious, Islamic identities as a means of reviving fertility. Ideally, a return to conservative versions of Islam might inspire Turkish (and specifically non-Kurdish) families to reassert traditional values and to have more children. Pious people, ideally, are breeding people.

For several reasons, then, in the current demographic environment, it makes excellent sense for a Turkish government to favor its poorer and more faithful population, to extol Islamic values, and to berate the “West” for its malign influences. Numbers alone mean that a leader has little to lose by espousing ever more vociferous Islamic policies and rhetoric, all of which are going to be well received in the Quran Belt. Whatever happens to Erdoğan personally, or to his party, those underlying demographic facts are not going to vanish overnight.

And that is why Hagia Sophia is going back to being a mosque.

This is adapted from my new book, Fertility and Faith: The Demographic Revolution and the Transformation of World Religions.