THE institutional voices of Sunni Islam have been slow to respond to the orgy of beheadings, mass-executions and sectarian cleansing promoted by jihadists of Islamic State (IS) in their so-called caliphate. So slow, in fact, that King Abdullah of Saudi Arabia last month publicly chastised the ulema, the body of clerics and scholars to whom ordinary Muslims are meant to turn for religious guidance, for their silence and “laziness”.

More recently, though, religious figures from across the spectrum of Sunni Islam have grown more strident. One group of liberal-leaning British preachers issued a warning for Muslims to shun the group, which it described as heretical, extremist and poisonous. Saudi Arabia’s senior official cleric, who represents the puritan Wahhabist school of thought, pronounced IS “the number-one enemy of Muslims”.

Several prominent sheikhs, who in the past have loudly championed jihadist groups including al-Qaeda, dismiss IS as modern-day Kharijites, a reference to fanatical “seceders” who in the first century of Islam declared all other Muslims to be infidels, and waged war against them. Abu Muhammad al-Maqdisi, a Jordanian preacher recently released from prison, accuses IS of driving a wedge between Muslims. His comments are striking because he was once spiritual mentor to Abu Musab al-Zarqawi, who led the forerunner of IS and was killed in an American air strike in 2006.

In a recorded “debate” over walkie-talkies with IS fighters that was broadcast on radio stations of rival rebel groups, a Syrian cleric, Sheikh Hussam al-Atrush, made every effort to expose their ignorance of Islam. Their so-called caliphate, he said, “has done nothing but incite hatred and disgust for the mujahideen.”

Raising the ante still further, Sheikh Nasser al-Shithri, an ultraconservative Saudi preacher, recently blasted IS, in effect excommunicating its adherents as “apostates worse than Jews, Nazarenes [Christians] or even heathens” who, he alleged, failed correctly to enforce Islamic law or even the proper veiling of women. Sheikh Saleh al-Fawzan, another prominent Saudi cleric known for extremist views (such as sanctioning slavery and counselling that Arab Muslims should be banned from marrying non-Arabs) decried the would-be caliphate as a creation of “Zionists, Crusaders and Safavids”—the last of which is an insulting reference to Shias. Other Wahhabist sheikhs have similarly claimed that IS leaders are secret agents of Iran, or of a broader Western-Shia conspiracy.

IS’s response has been muted. Unlike most jihadist groups, including al-Qaeda’s leaders, it has tended to shy from theological matters. Instead it simply issues videos of burqa-clad women in the caliphate, headless infidels and its demolition of Shia shrines. Sadly, for many its grim pictures are worth more than words.