The Near East School of Theology in Beirut is housed in a bland grey and brown building near the Mediterranean Sea. A few days ago, the audience in its underground lecture theatre was witness to one of the most remarkable lectures on ancient and modern Islam in recent times, which – had it been more widely advertised – might have had just about every shade of religious protester huffing and puffing outside in the aptly named Jeanne D’Arc Street.

The speaker was Dr Tarif Khalidi, one of Islam’s foremost scholars and translator of the latest English-language edition of the Koran, whose earlier works on Jesus in Muslim stories match his most recent anthology of Arab literature. The title of his address was an almost frightening world-beater: Does Islam need a Martin Luther?

Khalidi’s short answer was “yes, please”, the more Luthers the merrier – despite Luther’s violent indictment of Islam. It wasn’t clear whom Luther disliked more, the terrible Turk or the terrible Pope, and if you’ve got to shake up any religion you might as well do it “in as wonderful a cascade of rhetoric as his”.

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Khalidi recalled Lucretius’ castigation of all religions – “to so much evil can religion urge mankind” – and evil was all too obvious these days. It was obvious in all monotheistic religions, Khalidi insisted, “among certain so-called fundamentalist and apocalyptic sects in the US, among racist and fundamentalist settlers in Israel, among Daesh [Isis] and other horrifying groups in our own immediate neighbourhood.”

Khalidi, a generously-bearded Palestinian who talks English with TS Eliot precision, called all this the “Age of Dis-enlightenment”, which should move us to study “how and why religions can from time to time get lost, and mistake the road to heaven for the road to hell.”

Every 100 years in Islamic history, Khalidi observed, a renewer of faith – a mujaddid – would arise to breathe new life into the religion. The two “great wings” of Islam began their careers as reform movements, the Sunnis emphasising the importance of the unity of the community, the Shias emphasising the integrity of government, each splintering of these wings a form of reconstruction which now appear “like two great trees with numerous branches”.

And the most urgent task today? To “unpack” the ideas of Isis and to show how and why “its path leads to hell”.

There used to be a genuine if imperfect mosaic of tolerance in the Islamic world, Khalidi said, but the “ripping and shredding” of that tolerance “must be judged a travesty, an anomaly, a historical aberration of epic proportions”, which had its own antecedents.

Khalidi examined the Azariqa branch of the 7th- and 8th-century Khawarij movement. Long before Isis, Azariqa was condemning to death kafirs, unbelievers “…the Azariqa required recruits to their movement to kill a prisoner in order to prove their sincerity…they considered it legitimate to kill both the women and children of their enemies or else to enslave and forcibly rape women of different religions and sects…”

Khalidi took some comfort from the tendency of Isis, and its ancestors, to splinter violently, perhaps because of “their literal and highly selective use of sacred scripture, both Koran and ‘Hadith’ (sayings of the Prophet Mohamed) and their total indifference towards Islamic history, to say nothing of Islamic philosophy, theology…or Koranic commentary…”

The major horizon of Isis’s “speculative thought” appeared to be apocalyptic and thus an invitation to bring this about “through dramatic acts of suicide” – which the Khawarij used to call “selling one’s soul to God”.

I should add that the relevance of this theological lecture in Beirut was painfully evident less than 48 hours later when no fewer than eight suicide bombers, almost certainly from Isis and at least half of them Syrians, blew themselves up about a hundred miles from us, in the Lebanese Christian village of Qaa. Philosophy and violent reality have always been rather close to each other in Lebanon. But Khalidi was also talking about dialectic, the mutual arguments in which Muslim scholars in pre-modern history would discuss openly – though without resolution, for ‘God knows best’ – the meaning of holy texts.

In recent times, there had been a radical change, Khalidi said. Islam was invoked ‘from above’, which allowed modern preachers to assert final or unassailable views with phrases like “Islam forbids this but allows that” or “Islam teaches this and that”. This is a view which lends itself to the literalism of texts rather than argument, “happy in the pulpit and … happy issuing ‘fatwas’ on the most absurd grounds and topics, and unhappy when challenged.”

In pictures: Iraq battles to drive Isis out of Fallujah Show all 12 1 /12 In pictures: Iraq battles to drive Isis out of Fallujah In pictures: Iraq battles to drive Isis out of Fallujah Smoke rises after airstrikes by US-led coalition planes as Iraqi security forces advance against Islamic State extremists in Fallujah, June 15, 2016 AP In pictures: Iraq battles to drive Isis out of Fallujah Iraqi security forces advance during heavy fighting against Isis militants in Fallujah, Iraq, on 14 June AP In pictures: Iraq battles to drive Isis out of Fallujah Shia militia say that moving resources from Fallujah towards the area near Mosul was a 'betrayal' of the battle for the city GETTY In pictures: Iraq battles to drive Isis out of Fallujah Hospital sources said 18 bodies were recovered from the river over the weekend AP In pictures: Iraq battles to drive Isis out of Fallujah Up to 60,000 civilians were feared trapped in Fallujah at the start of the Iraqi operation AP In pictures: Iraq battles to drive Isis out of Fallujah Shia fighters hold an Isis flag in an operation east of Fallujah – the terror group has lost ground in both Syria and Iraq AFP/Getty In pictures: Iraq battles to drive Isis out of Fallujah Shia fighters hold their weapons as they gather near Falluja, Iraq, June 4, 2016. Reuters In pictures: Iraq battles to drive Isis out of Fallujah Pro-government forces bid to take back ground from Isis in Fallujah MOADH AL-DULAIMI/AFP/Getty Images In pictures: Iraq battles to drive Isis out of Fallujah Smoke billows on the horizon as Iraqi military forces prepare for an offensive to retake the city AP In pictures: Iraq battles to drive Isis out of Fallujah A member of the Iraqi security forces fires artillery during clashes with Isis militants near Fallujah, Iraq, 29 May, 2016 Reuters In pictures: Iraq battles to drive Isis out of Fallujah Iraqi government forces fire a rocket near al-Sejar village, north-east of Fallujah, on May 26, 2016, as they take part in a major assault to retake the city from the Islamic State group AFP/Getty In pictures: Iraq battles to drive Isis out of Fallujah Shia fighters and Iraqi security forces advance towards Fallujah Thaier Al-Sudani/Reuters

The scholar thus becomes a preacher. Ignore philosophy, theology, rationality. The Koran’s got all the answers.

And now for what is probably Khalidi’s most sentient point. “The rhetoric of Daesh [Isis] is merely the most virulent and violent form of this hijacking of authority, but the multiplication of absurd ‘fatwas’ by ‘ulama’ in totalitarian countries … is an equally pernicious phenomenon. Lamentable too and urgently in need of reconstruction is the proliferation of institutions and colleges which teach the bare rudiments of law and thus quickly graduate preachers … with an inadequate knowledge of other branches of Islam. This is particularly true of Sunni clerics whereas Shi’ite clerics, I would argue, are on the whole more broadly and more thoroughly trained.”

Now this is strong stuff to be heard in any society, let alone the modern (if that’s the right word) Middle East. But I preferred Khalidi’s even more powerful argument about education, which reflects also upon our Western world.

The Islamic curriculum is bleak, he claimed, “because the humanities in general are currently under siege in most universities of the world…history, philosophy, literature: these are disciplines and departments struggling desperately to survive in the Noah’s flood of career-oriented disciplines such as business or medicine or engineering or computer sciences…we must recognise that the humanities are crucial for the formation of a critical and sceptical intellect…when we demote and impoverish the humanities, we can confidently expect fanaticism to prosper.”

And there you have it: Khalidi divides Muslim thinkers into those who regard the Koran as the end of knowledge and those who regard it as the beginning of knowledge. The Koran should be used to question the world, “to confront its mysteries,” as Khalidi says, “treating Koranic language, as Matthew Arnold once advised us to treat the language of the Bible: fluid, passing and literary, not rigid, fixed and scientific.” Khalidi wants a committee of interpreters, a round table of Martin Luthers.