WASHINGTON -- It is not every day that one dines with the Sultan of Sokoto -- a direct descendant of Usman Dan Fodio, who was declared "Commander of the Faithful" in 1804 and founded a caliphate that reached from what is now Burkina Faso to Cameroon.

His Eminence Alhaji Muhammad Sa'adu Abubakar III is a thoroughly modern man of military bearing -- and perhaps the most influential religious figure you have never heard of. The sultan is spiritual leader to 70 million Nigerian Muslims. At home, he points out, a dinner at a restaurant is "quite impossible," because he would be mobbed by coreligionists. He speaks quietly, condemning religious "firebrands," and only showing unguarded enthusiasm when speaking of the Nigerian military, in which he served for decades as an officer, peacekeeper and military attache.

In America, religious leaders have difficulty making news even if they disrobe and juggle in the pulpit. In Nigeria -- half-Muslim, half-Christian and prone to violent rioting -- the wrong word from a religious leader could result in the death of thousands.

So it is symbolic that we are also dining in Washington with Dr. John Onaiyekan, the Catholic archbishop of Abuja. Together, as co-chairs of the Nigeria Inter-Religious Council, the sultan and the archbishop represent about 95 percent of their countrymen. They have known each other since Abubakar was a young officer ("We met soon after the attempted coup," reminisces the sultan). Now they travel together to speak on interfaith cooperation and tend to complete one another's sentences.

The two leaders are often forced to act as theological firemen, putting out the sparks of local conflict in Nigeria before they blaze. "When people start fighting," explains the archbishop, "it is rarely for religious reasons." The immediate causes have ranged from local politics to an altercation over a parking space. Police overreaction often makes things worse. But disorder can quickly take on religious overtones, requiring the leaders to intervene with traditional rulers and local religious leaders to keep the peace.

Both the sultan and the archbishop blame broad social challenges for Nigeria's tinderbox atmosphere -- frustration with government, poverty in the midst of plenty, even the unreliable electrical grid. But they also see what the sultan calls a "religious intensification" -- Pentecostals, gathered in camp meetings of hundreds of thousands, predicting the end times; Wahhabi Muslim influence from the Middle East; the advent of the Nigerian Taliban, imported, the leaders argue, from places such as Chad and Niger.

What is the long-term response to these religious tensions? Both leaders are dismissive of yet more interfaith "dialogue" (though they practice it well). "Discussion clarifies our differences, and we already know what those are," says the archbishop. Instead they are proposing the ecumenism of action -- building confidence and trust between their communities by cooperating against a common enemy.

The enemy they have chosen is anopheles gambiae -- the most dangerous malaria-carrying mosquito. Malaria is challenging for adults -- the archbishop describes his "twice-a-year appointment with malaria, when I lay in bed for three days" -- but the disease is often deadly for children, who have not yet developed immunity. And the mosquito makes no distinction between Muslim children and Christian children.

Nigeria has about a quarter of all the malaria cases in Africa. It is also beginning -- with the help of the World Bank, the Global Fund and the President's Malaria Initiative -- an effort to fight the disease, involving the distribution of more than 60 million insecticide-treated bed nets to 30 million families over the next 18 months. The scale of this effort is both vast and necessary. When about 70 percent of the households in a village use the nets, the entire village gains a halo of protection.

But reaching these goals in Nigeria is improbable without the active cooperation of mosques and churches. Houses of worship are distribution points where no clinic exists. And the effective, consistent use of bed nets requires education -- a perfect role for local, trusted religious leaders. So the sultan and the archbishop have launched an organization, the Nigeria Interfaith Action Association, to coordinate their efforts against malaria -- a plank across the Muslim-Christian divide.

It is true that religion can contribute to conflict, as thousands of dead Nigerians attest. But faith can also be a source of health -- as the sultan and the archbishop intend, and as hundreds of thousands of Nigerian children may live to witness.