In a house in Rafah, at the southern edge of Gaza, I met Sheikh Omar Hams, fifty-one years old, a slender figure dressed in a simple white robe and seated on a mattress on the floor. Hams is director of the Ibn Baz Islamic Institute, based in Rafah, where it also runs a bakery and charity outlets. His mission, he says, is to spread the word of the Prophet Muhammad and to give bread and other aid to the homeless and the poor.

Hams is a Salafist sheikh. “A Salaf means an original ancestor—one of those who lived close to the Prophet and observed his actions intimately, followed his ways and his words literally,” he explains. The sheikh teaches his students how to return to those ways, and they in turn spread the word. Unlike many Salafis, who abhor any rational argument about the literal meaning of the Koran, Hams is open to at least some debate. And though sometimes willing to support violent jihad, he accepts that violence is often not justified, preferring instead to secure a return to original Islam through the use of prayer, study, and preaching.

Pulling his legs underneath him, the sheikh prepares for questions on how the Prophet might have viewed the methods of Daesh (ISIS)—also Salafists—and on the battle to contain its influence across the world, most particularly here in Gaza.

Since 2007 Hamas has been the de facto government of Gaza, albeit under Israeli rule—a rule implemented nowadays by means of a military and naval blockade by air, land, and sea, which is described by the United Nations Secretary General, Ban Ki Moon, as “a collective penalty against the people of Gaza.” Hamas is itself an Islamist resistance movement, with a resistance “army” called al-Qassam, but Hamas members are seen as infidels by ISIS since they place the nationalist battle for a Palestinian state before the campaign for a caliphate. Hamas’s willingness to negotiate with Israel and to agree to a cease-fire last summer was seen by ISIS as the latest demonstration of its collaboration. ISIS supporters inside Gaza have shown their opposition and tried to break the cease-fire by firing rockets into Israel, thereby angering Hamas and risking heavy Israeli retaliation.

In recent months, Hamas has tried to crush groups of Salafi jihadists in Gaza, some of whom declare open support for ISIS and are in touch with its networks in Syria. As well as rounding them up Hamas has “persuaded”…