Remember the mania for lists as Y2K approached?

Discoverers of the 20th century. Cultural icons of the century. Explorers. Great leaders.

Conspicuous by their absence from these listings were the spiritualists of the past 100 years: men and women from the faith traditions who changed the way the world looked at God, man and man's place in the greater order of things.

This was a strange omission, indeed, at the end of a century that bore witness to The Great War, Auschwitz, Hiroshima, liberation theology, televangelism, the Second Vatican Council, unprecedented linkages between East and West and the spiritualization of human struggles against, among other things, war, racism, imperialism and the abuse of alcohol and drugs.

So who were the great spiritual leaders of the 20th century?

In his recently published book Spiritual Innovators: Seventy-Five Extraordinary People Who Changed the World in the Past Century (Skylight Paths, 259 pages), Ira Rifkin, an Annapolis journalist who specializes in religious topics, provides some fascinating answers to that question.

"We all know that the intense changes brought on by the 20th century were felt socially, culturally and politically," says Rifkin, whose insights into religious matters have been shared in numerous publications, Web sites, television shows and college classrooms for two decades. "Religion changed, too, which is hardly surprising. What was unprecedented, though, was the pace of that change. We were changed more quickly than at any time in history."

Rifkin and a colloquium of religious commentators brought together by Skylight Path, a small publishing house that has released dozens of books on spiritual matters, sifted through the many prospects appropriate for inclusion on such a list. From their deliberations came the 75 people whose minibiographies make up the volume.

"The theme of the book is impact," Rifkin says. "We selected people not necessarily because they were the holiest of the holy, but because of the profound influence they had on the spiritual directions the world took in the last century."

With that standard set firmly in place, some interesting names roll by. Philosopher-mathematician Bertrand Russell was an atheist, but his principled embrace of secular humanism made him a spiritual force to be reckoned with.

Robert Holbrook Smith, co-founder of Alcoholics Anonymous, is mentioned for elevating spirituality to a central place in recovery. "In Alcoholics Anonymous, you believe what you want to, but you surrender to a higher power," Rifkin says. "You acknowledge the pull of a force greater than your own."

That freedom of choice has created a spiritual eclecticism that is one of the dominant themes of the century and of the book. "Spirituality and religious belief have splayed out beyond denominational borders," the author says. "People feel more empowered to draw from different traditions."

Not surprisingly, then, this list of spiritual movers and shakers is diverse. Some leaders are included for the destabilizing power of their message.

Aimee Semple McPherson, the first Pentecostal preacher to use modern media to spread her message and one of the white clergy to reach out to the African-American population, is one; Elijah Muhammad, who linked Islam with black America, is another.

Gandhi, the Rev. Martin Luther King Jr. and Oscar Romero, the Salvadoran archbishop whose championing of the poor brought an assassin's bullet in 1980, are spiritual guides "who bore witness with their lives."

Others were included for their intellect, service to mankind, writing, penchant for religious pluralism and the power that their moral presence had on us.

From this project, it is clear that Rifkin's writings are worth watching for, particularly his soon-to-be-released Spiritual Perspectives on Globalization, a study of how eight religions have handled issues of economic and cultural change.

In the meantime, we're all the better for this volume, so full of informative sketches of those influential souls our popular culture all but ignored as the new century came upon us.