In 1916, Eugene Exman, a devoutly Christian teenager, was on his way to church when he encountered an inexplicable flash of light he considered a spiritual experience with God, one he longed all his life to find again. So begins author and Boston University religion professor Stephen Prothero's deeply researched biography of Exman and his decades in publishing in God the Bestseller: How One Editor Transformed American Religion a Book at a Time (HarperOne, Mar. 14). Prothero writes that Exman's work as an editor "helped to reimagine and remake American religion, turning the United States into a place where denominational boundaries are blurred, diversity is valued, and the only creed is that individual spiritual experience is the essence of religion."

Exman joined Harper & Brothers (precursor to Harper & Row, HarperSanFrancisco, and eventually to HarperOne) to direct their newly-launched religion book department in 1928. Rising to be a vice president of the company, Exman became "the undisputed standard-bearer for religion publishing in the United States," Prothero writes. The backlist he influenced is still earning millions. God the Bestseller lists scores of spirituality stars Exman published: Aldous Huxley, Houston Smith, Pierre Teilhard de Chardin, D.T. Suzuki, Martin Buber, and on and on. Prothero's book points to "Catholic radical Dorothy Day, the Civil Rights pioneer Howard Thurman, and two Nobel laureates: Albert Schweitzer and Martin Luther King Jr. ... He founded a club of mystics, dropped acid in 1958, four years before Timothy Leary. And six years before The Beatles went to India, he found a guru there in 1962."

By the time Exman retired from religion publishing in 1965, interest in Eastern philosophies was on the rise, and celebrities, New Age seekers, and dabblers in psychedelics joined scholars in detailing how they encountered the divine. Today's HarperOne—which is housed within HarperCollins rather than HarperCollins Christian Publishing—has published titles on wellness, the natural world, and inspiring memoirs alongside religion/spirituality titles under its umbrella. Gideon Weil, v-p and editorial director, tells PW, "At HarperOne, our authors have taken up (Exman's) charge. We publish books that inspire change, challenge preconceptions, and lead to transformation. We are publishing books for the world we want to live in."

Describing Exman as "a middlebrow publisher,' Prothero explores the editor's quest for a spiritual experience and how he helped open religion publishing to seekers and mystics as well as the leading thinkers in all denominations.

Exman's life story, you write, reveals the "stepping stones across the stream of American consciousness from Protestantism to pluralism, from dogma to experience, and from institutional religion to personal spirituality." How so?

He knew people wanted language they understood. He didn't want texts on theology. His editorial notes to authors were always urging them to make their work understandable and accessible to Christians and Catholics and Jews, to everyone. He edited the book by Bill Wilson (co-founder of Alcoholics Anonymous), who believed he had been saved from the ravages of alcoholism by divine intervention. Exman pushed him to cut the word 'religion.' And the book of AA became the idea of submission to a "Higher Power" instead. I don't agree with the idea that all religions are ultimately one, but I can appreciate the idea, if you consider that, after all, there is only one God and we need to find God in ourselves and be motivated to do good in the world. Exman, like William James (The Varieties of Religious Experience, published 1902), wouldn't distinguish among Buddhists, Christians, Jews, Muslims, and secular people who have these experiences.

What does the word "religion" mean today? As denominational distinctions lose their grip, is it all one wide path?

I know in religious studies now there is a real opening up in what counts as "religion." From CrossFit to street basketball to encounters with nature, people are finding what they consider authentic experiences of God. It's a real opening up in an Exman-y-like way: there's no idea of 'stop here and go no further.' And that's where publishing is heading.

If Exman were alive today what might he be publishing?

I think he would be intrigued by the cognitive science of religion. While he did publish a lot of academic and scholarly books, they didn't sell a lot. Now, he would publish cutting-edge scholars but also popular things like what parts of the brain are lighting up when you are meditating.

Your book asserts Exman "was a missionary for experience and a merchandiser in the attention economy" but ultimately his successes in the marketplace "crowded out his search for the divine. You can’t serve God and publishing." Can you talk more about this?

He was always trying to reflect and to lead the culture and connect the dots between spiritual experiences and social and political action. He saw his work as a calling to bring the best ideas to the public. It was his mission. He popularized the idea of the religion of experience. But the seeker inside him was always longing to see God again — and he didn't.