Before leaving the village, the attackers, driving over 3,000 stolen animals before them, tore up Korans found in the mosque and set the building on fire.

Barely a week later, the horsemen returned with soldiers from the regular Sudanese Army and in a four-day rampage killed 80 more people, including women and children. "The soldiers stayed on the edge of the village," said a 37-year-old man. "But they saw everything."

In the village of Sandikoro, soldiers and horsemen tore up Korans and defecated on them before burning the mosque, with its imam inside. In Sandikoro, they killed another imam, Abrahim Durra, as well as a second imam and the muezzin.

The story is the same across Darfur, Sudan's westernmost region. In 25 days of research there and among refugees on the border with Chad, Human Rights Watch documented 62 attacks on mosques in Dar Masalit, the homeland of one of Darfur's three main African tribes. Several of them were accompanied by murders inside mosques, often during prayer time. Korans, prayer mats and other symbols of Islam were routinely desecrated.

The Western world, reluctant to take the focus away from peace negotiations between the government and the Sudan People's Liberation Army (SPLA), has been shamefully late in acknowledging the atrocities in Darfur. But the Muslim world, even more shamefully, has yet to speak out.

The war in Darfur is in many respects a replay of the war in southern Sudan, waged with weapons that include ethnic militias, scorched-earth tactics and denial of humanitarian access. Both wars pit Sudan's Islamist, Arab-dominated government against African rebels demanding equal rights and an end to decades of neglect. In the south it is the SPLA that is doing the fighting; in Darfur it is the similarly named but quite separate Sudan Liberation Army (SLA).

But there is one big difference between the 21-year war in the South and the 15-month war in Darfur. The ethnic Africans of Darfur, unlike those of the South, are Muslim. And not just Muslim: deeply, devoutly, unshakably Muslim. Theirs is not the shrill, extremist Islam of the fundamentalist generals who seized power in Sudan in 1989, but a quiet, tolerant Islam that has characterized Sudan for most of its recent history and that still characterizes most of its citizens - Arab or African.

"Our Islam is good," says Izhaq Abdullah Adam Saber, 65, the imam of Kudumi village. "We pray all the time. We read the Koran all the time. It is they who are bad Muslims. Not us."

UN human rights investigators have accused the Sudanese government and the Janjaweed, the horse- and camel-riding Arabs who are fighting side by wide with the regular armed forces, of unleashing a "reign of terror" in Darfur. Senior UN officials have described the suffering there as "one of the worst humanitarian crises in the world." Some have gone so far as to draw comparisons with the genocide in Rwanda. The US Agency for International Development has warned that unless Khartoum breaks with past practice and grants full and immediate humanitarian access to the region, 100,000 war-affected civilians of African ethnicity could die in Darfur within the next 12 months

The government's swift and bloody crackdown on the rebellion in Darfur reflects the unique importance of the SLA rebellion within Sudan. For the uprising is not only proof of Muslim opposition to the country's totalitarian rulers. It is, perhaps even more importantly, a war that cannot be depicted as a rebellion against Islam. The rebels cannot be condemned as "infidels" as they were in the South. And so they are vilified as "thieves and robbers" - thieves and robbers, however, who have proved capable of mounting a formidable military challenge to a government that has the advantage of air power and the added punch of the Janjaweed.

The war in Darfur has laid bare the racial animus that has always underlain the war in Sudan. The killing there is not about religion. It is about race and ethnicity. In Darfur, the government's drive to "Arabize" a country that is made up of myriad ethnic groups has found a full and willing partner in Arab nomads whose search for new water and grazing land for their herds has led them into conflict with the majority population of settled African farmers.

When the SLA took up arms in February 2004, protesting government inaction in the face of increasingly violent encroachment by Arab nomads, the government responded by increasing its support for the nomads - reincarnated as Janjaweed - and embarked on a campaign of ethnic cleansing designed to lay waste the countryside and starve the rebels of support.

"The government wants to kill all African people, Muslim or not Muslim, in order to put Arabs in their places," says Izhaq Abdullah, unwittingly echoing the conclusion of many analysts. "We Africans are good Muslims. We pray all the time. We read the Koran all the time. It is they who are bad Muslims."