In the cemetery of Suleymaniye Mosque overlooking Istanbul’s Golden Horn lies the grave of Mehmet Zahid Kotku, an Islamic scholar and preacher who, although little-known outside of Turkey, was one of the country’s greatest proponents of political Islam.
For more than two decades until his death in 1980, he presided over the Iskender Pasa Mosque in the city’s conservative Fatih neighbourhood, where many devotees would go on to form the core of Turkey’s current political elite, including President Recep Tayyip Erdogan.
Under Kotku’s guidance, members of the Iskenderpasa lodge played a central role in forming a number of Islamist parties that culminated in the rise to power of the Justice and Development Party (AKP) in 2002.
The Iskenderpasa is one of hundreds of Turkish religious orders, with adherents estimated in the millions.
Observers argue that the most prominent – the Naqshbandi-Khalidi umbrella order that includes the Iskenderpasa – embraces an anti-western and anti-Semitic tradition that seeks to reverse the secularisation of Turkey implemented by Mustafa Kemal Ataturk, who won a war of independence to establish modern Turkey in 1923.
Mr Erdogan's frequent clashes with Europe and the United States, support for the Muslim Brotherhood and the positioning of Turkey as the leader of the Muslim world largely stem from this ideology.
On the domestic front, the promotion of Sunni Islam in education and the growing influence of the Directorate of Religious Affairs, or Diyanet, are also seen as symptoms of Naqshbandi thinking.
“If you look at all these figures in the AKP government over the years, you find a surprising number of them are linked not just to the Naqshbandi order but to one particular lodge, the Iskenderpasa,” said Svante Cornell, director of the Central Asia-Caucasus Institute and the Silk Road Studies Programme in Washington.
Although there is little concrete evidence to demonstrate the direct influence of Naqshbandi groups, many say their outlook dominates today’s political and business elites.
“The world view and the mentality and the ideology of this particular Naqshbandi group has defined Turkish Islamism,” Prof Cornell said.
Suleyman Cakmak, a Iskenderpasa member for more than 20 years and a board member of several foundations tied to the group, has few doubts about Mr Erdogan’s current stance.
“If you look at President Erdogan, who is himself a member of an arm of the Naqshbandi, he has a positive view of this issue,” he said. “He has been raised in this structure and comes from the same tradition so he has a positive view.”
While the president may not be as close to the order as before, he looks to it for “guidance and moral support,” Mr Cakmak added.
The Naqshbandi order spread to Anatolia in the early 19th century. Its sects were suppressed after Ataturk founded the republic but re-emerged during the Cold War as a bulwark against communism.
A decade after Kotku was appointed head of the Iskenderpasa in 1958, he backed the creation of Islamist parties that joined a succession of coalitions in the 1970s. In 1996, Iskenderpasa member Necmettin Erbakan became prime minister, only to be forced from office by the military the following year.
The perceived failure of political Islam in a subsequent election led to the formation of the AKP, with the party promoting a pro-western, pro-democracy image and playing down Islamist ties.
Another prominent figure to emerge from the Naqshbandi tradition was writer Necip Fazil Kisakurek, who advocated an Islamic revolution based on sharia that could counter the West’s “material and spiritual imperialism”.
He rejected democracy, calling for Turkey to be led by an “exalted leader”; proposed that Jews and other minorities be expelled from the country; and said Muslims should use state institutions to reverse secularisation.
AKP officials have done little to disguise their adoration of Kisakurek. Mr Erdogan regularly quotes his poetry and in 2002, when asked to identify the world figure that most inspired him, did not hesitate to name Kisakurek.
Deputy Prime Minister Besir Atalay, himself an Iskenderpasa follower, stated in 2013 that “the entire cadre that runs the country, including a large majority of the cabinet, were influenced by Master Necip Fazil [Kisakurek].”
When the AKP came to power, it styled itself as a conservative party akin to Germany’s Christian Democrats. However, in recent years, Mr Erdogan’s government has revealed an increasingly authoritarian nature.
Opposition MP Murat Emir underlined the threat to Ataturk’s principles. “Turkey is losing its secular character more and more every day,” he said. “You can see it in every aspect of life – our education system is getting more religious. Turkey is losing its democratic and secular character.”
The growth of Imam-Hatip religious schools is often cited as the realisation of a Naqshbandi goal. The number of Imam-Hatip students grew from 65,000 in 2002 to 1.3 million this year – growth that has been accompanied by increasingly religious content in regular state schools.
These developments have prompted some secular-minded parents to complain that their children are forced to sit in classes that place too much emphasis on Sunni Islam.
The Diyanet, which was previously limited to providing imams and sermons, has had its budget quadruple since 2006 to more than $2 billion (Dh7.35bn), becoming larger than the Interior Ministry.
The directorate has come under fire for ignoring the needs of religious minorities such as the Alevi community, who form a fifth of Turkey’s Muslims.
Abroad, Turkey recently has turned from the West to seek ties with Russia, China and states such as Sudan. “If you look at the priorities of Turkish foreign policy you see clearly the influence of ideology,” Prof Cornell said.
“It’s very clear if you look back at Egypt, Hamas and Sudan, you have the AKP taking stances that can only be explained by a proclivity for Sunni Islamist movements.”
Egypt’s Muslim Brotherhood is viewed by many as the bedfellow of Naqshbandis due to a shared orthodoxy and politicised nature.
As the Arab Spring erupted in 2011, the AKP saw a chance to “restore Turkish greatness and Turkish influence over the Middle East by supporting the Muslim Brotherhood and helping them come to power,” Prof Cornell said.
However, this failed “because it wasn’t guided by pragmatic thinking, it was guided by ideology”.
Conflict with the West over issues such as Syria and the jailing of US and European citizens has led many to the suspicion that Turkey is turning away from its Nato partners and the goal of EU membership.
However, many see this anti-western outlook as having always been present in Turkish political Islam.
“If you look at the emergence of the world view that Erdogan stands for, it’s amazing how little it’s changed,” Prof Cornell said. “There is continuity in his actions, there is a larger scheme and a larger purpose. He genuinely views himself as the representative of a much larger cause.”
However, Mr Emir, the opposition MP, said Mr Erdogan’s “defiance” of the West is shaped by pragmatism. “It’s useful for a Turkish audience but at the end of the day, he agrees to everything the US or other western countries want.”
For the Iskenderpasa’s Mr Cakmak, the anti-western strand stems from a “collective reaction” to imperialism and colonialism.
Diyanet officials were unavailable to comment but earlier this month, the directorate’s head, Ali Erbas, said: “There are structures that abuse religion, make a profit out of it. There are some who act out of the rules and principles of Islam. We as the Diyanet warn those who make mistakes and will continue to do so.”
However, with the 2016 coup attempt – widely blamed on the Gulenist sect that had infiltrated the state – fresh in people’s minds, the influence of unregulated religious orders raises concerns.
“Everyone should ask why a religious order should try to collect power, money and people in the state,” Mr Emir said. “We should be alert that, in time, they will use this power.”