Washington: Turkey is a Muslim house divided – and as the factions nip and tear at each other, President Recep Tayyip Erdogan's increasingly autocratic tendencies stoke a war between old friends.

On one side and with much of the power is Erdogan and his Justice and Development Party (AKP); on the other, is the self-exiled and hermit-like Fethullah Gulen, who lives in Pennsylvania in the US, from where he pulls the strings of a movement that is embedded in key government institutions and departments.

Such is the enmity, that what each says about the other must be taken with a large grain of salt.

In one of his first television appearances after the attempted coup was launched, Erdogan lashed out, accusing the perpetrators of treason, ordering their military aircraft to be shot from the skies – and charging that this 'minority' within the military had acted on orders from the cleric Gulen.

A statement released under the banner of the Alliance for Shared Values, a part of the Gulen network in the US, claimed that Gulen and his followers had consistently denounced intrusions– "we condemn any military intervention in domestic politics of Turkey."

And the analysis offered to Fairfax Media by one of Gulen's followers was worthy of Machiavelli – but because this it Turkey and we're talking about a president who wears his paranoia on his sleeve, it can't be dismissed out of hand.

Here's the Gulen line – Erdogan had stage managed the whole coup crisis as a pretext to impose martial law, under which he could ram through sweeping constitutional changes that might legally, if not morally, legitimise his bid to consolidate great power in his presidential office which, legally, remains a titular post.

In Turkey, the Gulenists operate under the name Hizmet, or Service, and they claim their objective is democratic accountability. But they are so entrenched across government that Erdogan blames them for everything – this week, it's the attempted coup; in 2013, it was for manipulating the police, prosecutors and the judiciary to expose rampant corruption, involving some of Erdogan's family and some of his closest associates.

Perhaps the best parallel by which the Gulen-Erdogan relationship can be explained is the deal between the House of Saud and the Wahhabi Islamic sect in Saudi Arabia, by which the shared responsibility for different sections of government mutually reinforces the two power bases.

But while the Saudi deal holds, the Turkish deal fell apart, turning the best of friends into sworn enemies.

Gulen, 79 years old and a diabetic, runs an international Islamist network purportedly operating in more than 150 countries, including Turkey where it focuses on educating young Turks to take their place in the judicial and police services, in particular.

Gulen fled to the US in 1999 and was tried in absentia for conspiring against the then secular Turkish state. Part of the evidence was a video in which Gulen tells supporters: "You must move in the arteries of the system, without anyone noticing our existence, until you reach all the power centres… You must wait until such time as you have gotten all of the state power".

In a 2009 cable, made available through WikiLeaks, former US Ambassador James Jeffrey reports that in Turkey, the Gulen political agenda is seen as "possibly insidious". Elsewhere, Jeffrey describes the movement as "having perhaps millions of followers, [is] worth perhaps billions, and with a presence, often through its high-achieving schools, in 150 countries".

The movement operates 135 charter schools in the US; and in Turkey, it has eight universities, dozens of private schools and hundreds of "cramming" centres that prep youngsters for vital university entrance exams.

Gulen has ignored several Fairfax Media requests for an interview. But in a rare encounter with the BBC early in 2014, Gulen denied Erdogan's charge that he was the instigator of the sensational corruption probe in Istanbul.

It was a curiously unrevealing encounter, in which Gulen opted for sarcasm to make his point: "People in the judiciary and the police carried out investigations and launched this case, as their duties normally require. Apparently they weren't informed of the fact that corruption and bribery have ceased to be criminal acts in Turkey."

Analysts describe Gulen's organisation, funding and influence as "formidable" and there are detailed accounts from within the police force of how jobs, pay and promotions are controlled by his associates.

Erdogan reluctantly acknowledged that from the start, his government was based on an informal deal in which the quid pro quo was that Hizmet won a significant footing in the bureaucracy, particularly in law and order and the judiciary, and in return, Gulen used his considerable business and diplomatic connections to open doors for Erdogan, at home and abroad.

The movement has been something of a sophisticated attack dog for Erdogan's AKP. As explained by the Turkey analyst Halil Karaveli, Erdogan needed its well-educated members and supporters to help run the country – especially the police and the judiciary. That was the deal – if Gulen endorsed the AKP and its candidates, he would get effective control of swathes of the bureaucracy.

But over time Erdogan became distrustful – and guerrilla war ensued. As prime minister at the time, Erdogan set about purging Gulenists from party lists. Then he wanted them weeded from the bureaucracy.

The Hizmet university prep centres were deemed to be a threat to the national good and ordered to close. Writing in Foreign Affairs, Karaveli explains: "The Gulen movement retaliated by supporting a corruption probe…against several cabinet members and businessmen with close ties to the government.

So it was something of a cathartic moment in Turkish history when, in February 2014, a session of Erdogan's National Security Council, which included the top generals, voted to list the Gulen movement as a threat to national security. Reportedly declaring 'total war' on the movement they approved the purging of government agencies of Gulenists.

And weeks later Erdogan declared himself to have been naive to allow the movement to acquire so much power.

In January 2014, a government insider told the The Telegraph in London that Erdogan worried that the loyalty of Hizmet members on his payroll lay more with Gulen than with Erdogan. "He fears they are plotting to destroy him," the paper was told. "He feels threatened."

After Erdogan met with European leaders early in 2014, a senior EU official in Brussels told The Guardian: "He was gripped with this obsession of killing the parallel state, as he called [the Gulen movement]."

In an overwrought victory speech after local government elections in March 2014, Erdogan warned that he was after Gulenists, declaring: "We'll walk into their dens… They will pay for this."

Gulen and his defenders claim he has no interest in political power. Writing in Foreign Affairs, Gulen associate Y. Alp Aslandogan argues that Gulen could not have stacked the judiciary with his followers because so many powerful figures had stacked it before him.

He writes: "In their projects focused on education, health care, humanitarian assistance and intercultural dialogue, [the movement] is driven by intrinsic rewards alone."

But the writer and Gulen associate Huseyin Gulerce acknowledged a clash of ideas and ideals between Gulen and Erdogan when he told The New York Times that Gulenists shared many of the complaints of the Gezi Park protesters – the then prime minister had become too powerful, too authoritarian and has abandoned the democratic reform agenda that underpinned Turkey's bid for membership in the European Union.

"This is not a group that Mr Erdogan is not familiar with," Gulerce said at the end of 2013. "He knows all of us personally; from the time he was mayor of Istanbul. He has known Mr Gulen personally for 20 years."

Gulen insists he is without power in the Turkish equation. But he too seemed overwrought in a December [2013] sermon, in which he inveighed against Erdogan. Without naming the prime minister, Gulen lambasting those "who turn a blind eye to the thief while punishing those who prosecute the thieves." And he climaxed with a plea to God to "consume their homes with fire, destroy their nests, and break their accords."

When I talked to Ersin Kalaycioglu, a political science professor at Istanbul's Sabanci University, he observed that in the past Erdogan would not allow criticism of the Gulenists. "Now he wants us to believe that he was naive and deceived – only a person with no intelligence can be expected to believe that."

In 2006, Erdogan arranged Gulen's acquittal on the previous regime's charge that Gulen had attempted to take over the state. Now, the prime minister had changed his mind, unsuccessfully demanding that the US extradite Gulen back to Turkey to face accusations from his former comrade, Erdogan, that are remarkably similar to those Gulen faced from the generals in the 1990s – that he infiltrated government agencies with a view to taking over the state.

Trying to unravel the Erdogan-Gulen conundrum, Istanbul based writer Suzy Hansen writes: "If a [president] can co-opt the laws and the media, and if a self-interested group can prosecute trials of dubious legality, and if citizens have no where to express themselves but in the streets, then the state institutions are broken."

But Ersin Kalaycioglu, the professor of political science, warned that the president's skill as a political street fighter could be discounted. "Erdogan has not lost his capacity," he told me. "He's still very effective at communication his message. He got 43 per cent of the vote in the March local elections – he was able to convince that many people that he is the victim of a conspiracy."

The analyst Karaveli had a different read on the public mood in Turkey. Noting the outcome of an opinion poll in which there was 6 per cent for Gulen and 28.5 per cent for AKP, and in which 45 per cent of respondents faulted them both, he went to the issue of a Muslim house divided: "This AKP-Gulenists backbiting represents a massive and collective failure of the Islamic conservative movement, from which none of its components may be able to recover."

Erdogan is unrelenting in his pursuit of Gulen. At the end of June his most recent effort was rebuffed by a US court, sitting in Scranton, Pennsylvania, threw out an action taken on Erdogan's behalf and reportedly funded by the Ankara government, to sue Gulen on the grounds that he had manipulated the corruption scandal to embarrass Erdogan.

Follow Fairfax World on Facebook

Follow Fairfax World on Twitter