On Friday, the media reported that ISIS, the Islamist group that has established a “caliphate” in parts of Syria and Iraq, had destroyed the centuries-old Tomb of Jonah in Mosul, Iraq. Present-day Mosul encompasses the site of the ancient Assyrian capital of Nineveh, where, the Bible teaches, the Prophet Jonah preached. Although this is disputed, a tradition holds that Jonah was buried within the city, on Tell Nebi Yunus, or Hill of the Prophet Jonah.

An Assyrian church stood over the tomb for centuries. After the Muslim conquest, the church became a mosque; the structure that ISIS destroyed last week dated to the 14^th century. In addition to the tomb, the mosque once held the supposed remains of the whale that had swallowed Jonah, including one of its teeth. At some point, even the tooth had disappeared. In 2008, the U.S. Army presented the mosque with a replica.

Last week, ISIS closed the mosque and prevented worshipers from entering. Then it wired the structure with explosives and reduced it to rubble (above). You can see a video of the explosion here, taken by a Mosul resident, who mutters, in Arabic, “No, no, no. Prophet Jonah is gone. God, these scoundrels.”

Some commentators have explained the destruction of the tomb as part of ISIS’s anti-Christian campaign. Scholars Joel Baden and Candida Moss point out that, in Christian interpretation, the Old Testament story of Jonah prefigures the death and resurrection of Christ. “The destruction of his tomb in Mosul is therefore a direct assault on Christian faith, and on one of the few physical traces of that faith remaining in Iraq.” Another scholar, Sam Hardy, told the Washington Post that the destruction of the tomb shows that ISIS is willing to destroy “pretty much anything in the Bible.”

On this analysis, ISIS destroyed the tomb because of its Christian associations. But that mistakes ISIS’s motives in this case. True, ISIS has no respect for Christians or their sites of worship and, in fact, has driven Mosul’s Christians from the city. The fact that the tomb was sacred for Christians as well as Muslims—and contained a present from the US Army—cannot have endeared it to ISIS. But something else is going on here. The shrine was, after all, a mosque, and Jonah figures in the Quran as well as the Bible. To understand why ISIS destroyed the tomb, one has to appreciate something about the version of Islam the group espouses.

ISIS is part of the Salafi movement, a branch of Sunni Islam that seeks to return to the practices of the earliest Muslims – the salaf— who lived at the time of the Prophet Mohammed and just after. The movement rejects the centuries of subsequent developments in Islam as unjustified innovations–pagan accretions that adulterated the faith. In particular, the movement opposes the veneration of the graves of Islamic prophets and holy men. Salafis see this practice, which is associated most frequently with Sufi Islam, as a kind of idolatry, or shirk, that detracts from the absolute transcendence of God.

Salafi Islam prevails in Saudi Arabia, where it enjoys the patronage of the royal family. On the Arabian Peninsula, as now in Iraq, Salafis have destroyed the tombs of Islamic holy men. Indeed, when the Saudi royal family captured the city of Medina in the 19^th century, Salafis systematically destroyed the tombs of several of the Prophet Mohammed’s companions and family members, leaving only the Prophet’s tomb itself unmolested. There is some thought that the Saudi government plans on dismantling even that tomb, but hesitates to do so because of the uproar that would result in other Muslim communities.

In short, one should see ISIS’s destruction of the tomb of Jonah as an act principally directed at other Muslims, not Christians. That doesn’t make it any better, of course. Will the outside world do anything in response? Unlikely. Besides, as Professor Hardy told the Post, “If we didn’t intervene when they were killing people, it would be kind of grotesque to intervene over a building.”