Beirut: Turki Al Binali has criss-crossed Daesh’s self-declared caliphate in Syria and Iraq with a pistol holstered at his side, delivering fiery sermons in which the 30-year-old provides religious justification for its bloody rampage across the region.

The young Bahraini preacher, who has emerged as one of the extremists’ leading ideologues, promotes a version of Islam that has been rejected, not only by mainstream religious authorities, but even by veteran militant clerics now increasingly out of touch with the new generation of radicals.

Al Binali, who sports long hair and a dark beard, is not the most senior cleric in the group — that title belongs to a secretive Iraqi named Abdullah Abdul Samad — but he is perhaps the most visible, said Hisham Al Hashimi, an Iraq-based researcher who closely follows militant Islamist groups.

“He is a very important part of the religious council of Daesh,” Al Hashimi said. “He is like the fence that defends the ideology of Daesh from penetration.” Al Binali also wrote the official biography of the group’s leader, Abu Bakr Al Baghdadi.

The young preacher has given lectures and engaged online with critics and supporters. His edicts and statements are printed and distributed in areas under the group’s control, said a Daesh group fighter in Syria, who spoke on condition of anonymity because he is not a spokesman for the group.

Al Binali hails from a prominent Bahraini family and rose to become a well-known figure in the tiny Gulf nation’s ultraconservative Salafi movement. He studied for a time at Dubai’s Islamic and Arabic Studies College but was deported because of his ideology, according to a biography written by Austrian militant Mohammad Mahmoud. He continued his studies at Islamic universities in Bahrain and Beirut before travelling to Syria last year and joining Daesh, according to militant websites.

In a photo posted on militant websites, he’s shown in a mosque in the northern Iraqi city of Mosul in July, wearing a white gown and turban with a pistol holstered under his arm, preaching to dozens of worshippers and fighters.

In its march across the region, Daesh has massacred hundreds of captives, mainly Syrian and Iraqi soldiers, sometimes displaying their heads in public squares. Its clerics have justified such acts by citing a verse from the Quran.

The extremist group also has beheaded two American journalists, two British aid workers and an American aid worker. It presented the killings as a response to US-led air strikes and said it was justified in beheading the five captives because they had entered territory controlled by the extremists without an agreement of protection. A German journalist received such protection and was allowed to report on the group late last year before returning unharmed.

Al Binali himself has provided religious justification for the enslavement of hundreds of women from Iraq’s Yazidi minority.

Writing in an online forum, he said: “There is no doubt that enslaving women of infidel warriors” is permitted. He pointed to a religious opinion by a 13th century cleric who said that in wartime, “it is not permitted to kill women and children but they become slaves to Muslims.”

Leading Islamic authorities have condemned Daesh’s atrocities and rejected its self-styled caliphate as illegitimate because it was declared unilaterally without the consensus of established clerics. But such criticism matters little to the militants, who view mainstream religious authorities as tools of the region’s states.

More problematic is pushback from veteran militants, including some closely affiliated with Al Qaida. Daesh broke away from the global network founded by the late Osama Bin Laden in 2013 over a bitter ideological rift, and has battled Al Qaida’s affiliate in Syria.

Abu Mohammad Al Maqdisi, a Jordanian cleric who once mentored Abu Musab Al Zarqawi, the slain head of Al Qaida in Iraq, has condemned Daesh’s brutality. Abu Qatada, another radical Jordanian preacher deported from Britain, described its members as “criminals.” And Al Qaida’s powerful Yemeni affiliate has explicitly rejected the beheading of captives.

But when it comes to recruiting a new generation of radicals, Daesh has been buoyed by its sleek online media operations and its battlefield successes.

“There is certainly an issue of generational divide here: that [Daesh] is attracting the younger ‘intellectuals’ and fighters,” said Ayman Al Tamimi, an expert on Syrian and Iraqi militants.

Al Binali has struck back at his mainstream critics, disputing the widespread comparison of the Daesh to the Khawarej, an early Islamic movement that later generations of scholars considered so extreme as to have left the faith entirely.

But as recently as November he warned the leadership of his own movement that it faces “slow collapse” unless it can get well-known extremist clerics on board, according to an anonymous Twitter account called “wikibaghdady” that frequently publishes inside information about the group.

There is no independent confirmation of the “wikibaghdady” reports, but Radwan Murtadha, an expert on militant groups who writes for Lebanon’s Al Akhbar daily newspaper, said he believes the reports are largely accurate.

After Al Binali’s appeal, the leadership gave him the green light to approach clerics from Jordan, Saudi Arabia, Morocco, Yemen and elsewhere to try to win them over and convince them to come settle in Daesh group-controlled areas, according to the Twitter account.

The unnamed clerics rejected the offer, it said.