The political crisis now gripping Turkey is the country’s second in half a year. Last summer, millions of liberal Turks spent weeks in Istanbul’s Gezi Park and in the streets of other Turkish cities to denounce their increasingly pious, authoritarian, and plutocratic government, but the prime minister, Recep Tayyip Erdoğan, was never really under threat. The popular support he enjoyed was much greater than his opponents’. The latest crisis, which began with the arrest of dozens of prominent pro-government figures on December 17, and has continued to spread through ever since, is quite different. It emanates from the prime minister’s own circle of power and pits two groups against each other that are entrenched in virtually all administrative and commercial areas of Turkish life: Erdoğan and his AKP government, on the one hand, and an exiled spiritual leader, Fethullah Gulen, whose powerful religious and social movement has acquired sweeping influence, particularly in the police force and the judiciary, on the other.

Because the conflict is between insiders, it could unfold more dangerously than Gezi, which had a sadly predictable denouement. (The protesters were crushed by the forces of law and order and went home.) With the ability to affect government, business, and the law on many levels, it threatens to undermine years of political stability. The effects are not only political; this week, the Turkish central bank has called an emergency meeting to try to stave off the collapse of the Turkish lira, amid fears that a decade of economic prosperity may also be threatened.

Beatific, primly mustachioed, exquisitely self-deprecating in the manner of the Sufi sage, Fethullah Gulen has lived quietly in exile in the United States for more than a decade. But he controls a movement that has no formal boundaries, and which is all the more menacing to Erdoğan as a result. Conveniently removed from the rough and tumble of Turkish public life, but free to meet any admirer who cares to visit him, his captivating presence and enthusiasm for private enterprise have drawn pious Turkish businessmen into an ever-expanding web of profit, philanthropy, education, and schemes of spiritual uplift. An organisation without a declared membership or leadership structure, the Gulen empire is thought to encompass more than five hundred fee-paying schools in one hundred countries (including the United States), along with banks, hospitals, media groups, and a business association, Tuskon, which has spearheaded the Turkish penetration of new markets, notably in Africa.

Arguably Gulen’s most important asset is the community of volunteers, donors, and sympathizers he has at his command—five million of them according to some estimates, the vast majority in Turkey but many also spread across Turkic Central Asia and elsewhere. Gulen’s prodigious output of sixty books, mostly on religious topics, and regular sermons, the latter disseminated on the Internet (the movement controls some twenty-five websites) has kept people abreast of his message of peaceable Islam, hard work and Turkish revival.

Erdoğan’s AK Party came to power in 2002, and for the rest of the decade his policies of economic and political liberalization, under an increasingly religious state, were in harmony with the teachings of Gulen himself. Gulen’s supporters voted for the AKP and contributed to its coffers; some of them entered parliament as AKP deputies. The two men were also at one in endeavouring to dismantle the secular apparatus of the state, from which both had suffered in the past. (In 1999 Erdoğan spent four months in jail for reciting verses with an aggressively Islamist theme.) Prosecutors aligned with Gulen are widely believed to have engineered the recent mass trials of senior members of the military and the old secular establishment, which culminated last summer in the imprisonment of dozens of retired army officers, including a former chief of the general staff, on much inflated charges of planning to a coup. Pro-Gulen prosecutors and journalists are vigorous in defence of the hocaefendi, or “esteemed teacher”–as judicial processes and smear campaigns that have been launched against Gulen’s critics attest. Gulen protests that he is a fakir, or pious “beggar,” but many of his followers regard him as a prophet-like divine, whose teachings reflect the light of God.

One can well imagine how an opaque and unregulated movement such as the Gulenists might come into conflict with a government occupying the same ideological terrain, jealous of its prerogatives and increasingly tarnished with allegations of corruption. And this is what has happened over the past few years, with deceptive gradualness. In 2012 a Gulenist prosecutor attempted (without success) to summon Erdoğan’s intelligence chief for questioning. The government has been threatening to clamp down on Gulen-affiliated schools; Gulen’s supporters complain that they are being denied civil service jobs because of their loyalties across the Atlantic, while the hocaefendi has taken to denouncing “Croesus” and “Pharaoh” in his sermons—references, it is thought, to the prime minister himself.

The recent crisis began when some fifty prominent government supporters were taken in for questioning by Gulenist prosecutors, including three sons of cabinet ministers and the chief executive of a state-owned bank, Halkbank. The Turkish press reported that some $4.5 million had been found, stashed in shoeboxes, in the home of the Halkbank executive. Ten cabinet ministers resigned and others were replaced by Erdoğan, apparently because of the possibility that they could be implicated in the investigation; the prime minister meanwhile warned darkly of a “parallel state” within the police force and the judiciary that has been plotting against his government. Inveterate conspiracy theorist that he is, however, Erdoğan has also blamed the case on unnamed foreign enemies, who he accuses of acting in unison to try to stop the country’s rise.

The prime minister quickly struck back. Mass transfers of Gulenist personnel in the police and judiciary have had the effect of halting the corruption investigation (the prosecutors who initiated it have been removed), while a second phase of the same enquiry, touching on the government’s relations with construction companies and the friendship between the Erdoğan family and a controversial Saudi businessman, has also stalled. On January 6, Erdoğan indicated that he would support moves to reopen the case against the secularists, who were convicted by Gulenist prosecutors last summer. Clearly he hopes to discredit the prosecutors who orchestrated it. The government has also introduced legislation that would allow it to make appointments at the top of the judiciary, while pro-Gulen media has accused the government of bias against businesses associated with the exiled preacher—this after a period when some Gulenist enterprises have enjoyed government favor.

Fethullah Gulen is a public figure of resilience and longevity; it is hard to imagine the government successfully restraining his movement. Born in 1938 in eastern Turkey, he spent the first two decades of his working life as an imam on the government payroll, interrupted by a seven-month spell in jail following the coup by the Turkish military in 1971, when Islamists and Communists alike were put behind bars. He eventually went freelance and in the 1980s his renown as a preacher and inspiration behind a network of highly successful private schools brought him more attention from the authorities. In 2000, having travelled to the United States for medical treatment (he has diabetes and an iffy heart), Gulen was tried on charges of trying to overthrow the state, and he has never returned—even after being acquitted in 2006. In 2008 Gulen was granted permanent residency in the United States.

Meanwhile, the Gulen movement has acquired considerable reach across Turkish society. Each year, more than three quarters of a million young people pass through Gulen-affiliated crammers, where they have been prepared for university entrance exams, and the excellence of the instruction on offer is evidenced by their matriculation at the best universities; they go on to occupy influential positions in academia, business, and the Turkish bureaucracy. The Gulenists also influence the Turkish public debate through their media holdings, which include Zaman newspaper, one of the country’s biggest. Imagine a Mormon Ivy Leaguer with friends in the Grand Lodge and you will have some idea of the connections that Gulenists can call upon in Turkish society.

The conflict currently playing out has the potential to paralyze many institutions of the Turkish government, further damaging an administration whose international credibility has already fallen precipitously as a result of the failure of its aggressive policy towards Syria. Instead of spearheading the successful overthrow of Bashar al-Assad, Turkey has alienated former allies while bringing instability—from Syrian air strikes, radical Syrian opposition groups, Kurdish militias, and overwhelming numbers of Syrian refugees—to its own southern border. Now, with investor fears driving the Turkish lira down sharply, Erdoğan’s AKP now faces local elections (in March) at a moment when the economy is increasingly adrift. Turkey depends on short-term inflows of foreign capital to service its high external debts, and there are increasing fears in international financial markets that that foreign capital will quickly be withdrawn if the equilibrium between the different branches of government continues to erode.

And while Erdoğan is a political bruiser of impressive durability, he now faces in Gulen an elusive foe who comes from the old Ottoman tradition of the charismatic holy man. Revered by their followers, their powers embellished by hearsay and rumour, these divines acquired considerable unofficial power in the Ottoman period, acting as a check on the sultan’s authority. Last month Gulen did not shrink from placing a malediction on his enemies, beseeching God to “consume their homes with fire, destroy their nests, break their accords.” This year, Erdoğan has set himself the task of keeping Istanbul and other key municipalities in AKP hands—and, perhaps, standing for the presidency when Turkey’s first direct elections to the post are held in August. But now, for the first time in his career, the Gulenists stand in his way.