The era of world struggle between the great secular ideological -isms that began with the French Revolution and lasted through the Cold War (republicanism, anarchism, socialism, fascism, communism, liberalism) is passing on to a religious stage. Across the Middle East and North Africa, religious movements are gaining social and political ground, with election victories by avowedly Islamic parties in Turkey, Palestine, Egypt, Tunisia, and Morocco. As Israel's National Security Council chief, Gen. Yaakov Amidror (a religious man himself), told me on the eve of Tunisia's elections last October, "We expect Islamist parties to soon dominate all governments in the region, from Afghanistan to Morocco, except for Israel."

On a global scale, Protestant evangelical churches (together with Pentacostalists) continue to proliferate, especially in Latin America, but also keep pace with the expansion of fundamentalist Islam in southern Africa and eastern and southern Asia. In Russia, a clear majority of the population remains religious despite decades of forcibly imposed atheism. Even in China, where the government's commission on atheism has the Sisyphean job of making that country religion-free, religious agitation is on the rise. And in the United States, a majority says it wants less religion in politics, but an equal majority still will not vote for an atheist as president.

But if reams of social scientific analysis have been produced on religion's less celestial cousins -- from the nature of perception and speech to how we rationalize and shop -- faith is not a matter that rigorous science has taken seriously. To be sure, social scientists have long studied how religious practices correlate with a wide range of economic, social, and political issues. Yet, for nearly a century after Harvard University psychologist William James's 1902 masterwork, The Varieties of Religious Experience, there was little serious investigation of the psychological structure or neurological and biological underpinnings of religious belief that determine how religion actually causes behavior. And that's a problem if science aims to produce knowledge that improves the human condition, including a lessening of cultural conflict and war.