Sometime last year I had an interesting informal conversation with Richard Mouw, the president of Fuller Theological Seminary, a respected center of Evangelical scholarship and learning. Mouw has spoken on this program in the past about his path from a fundamentalist childhood to life as an Evangelical intellectual and Christian philosopher. As he describes it, this faith of 25-40 percent of the U.S. population, depending on how you count it, has no single central authority, no ultimate hierarchy, nothing like a pope. But it does have what Mouw calls a "magisterium" — guiding figures in every generation. I'm intrigued by what seems a changing of the guard in that magisterium. Figures like Billy Graham and Chuck Colson, Jerry Falwell and Pat Robertson, James Dobson and Ted Haggard, have passed or are passing from center stage. Of those who are emerging, Rick Warren is the biggest surprise to many. Warren has received a huge amount of media coverage in recent years. He burst into popular imagination largely by way of his 2002 book, The Purpose Driven Life, which Publisher's Weekly has called "the best-selling non-fiction book in American history," now approaching sales of 35 million. But for a time even that phenomenon was easy to miss. It was not immediately noted by major media and bestseller lists — it did not appear on The New York Times non-fiction bestseller list, for example — because it sold mostly through Christian bookstores and via Warren's global online networks of pastors. He created this book with the same pragmatic strategic vision that launched his 100,000-member Saddleback Church in Orange County, California, one of the original megachurches. "Megachurch," I know, is a suspect concept to some. But understanding what the Warrens have created at Saddleback is key to understanding who they are and what kind of influence they've begun to exert beyond it. As they describe in our interview, Rick and Kay Warren pitched their tent, almost literally, in this nearly empty valley near Los Angeles in the mid-1970s, ready to build a church and stay for their lifetimes. Rick Warren had studied the 100 most successful churches in the world. He also sought out the great organizational management guru Peter Drucker as a mentor; Drucker later called Saddleback Church "the R&D department of Christianity." So Rick and Kay Warren knocked on doors and asked people what alienated them about traditional churches, and what might bring them back. They designed their church with this input and waited for the area to fill up with houses and families, which it did. Behind a comfortable, easy welcome to worship, they invited members into layers of study, community, commitment, and service. Rick Warren originally conceived The Purpose Driven Life as one such study course for his congregation. Now congregations all over the world have embarked on a "Forty Days of Purpose" course that corresponds to the book, Rick Warren's curriculum towards deepened individual and communal faith and calling — Christian purpose. Rwanda is the focal point of the latest chapter of Rick Warren's ministry — a turning point, and his own reevaluation of the meaning of "Christian purpose," largely due to Kay Warren's influence. This is why I wanted to interview them together. As Kay Warren tells it, in the wake of the wealth and fame that followed the success of The Purpose Driven Life, she had a life-changing "awakening" to the pandemic of AIDS and the attendant ills of poverty. This transformed her understanding of the essence of Christian faith and that of her husband. She has publicly urged her congregation and others to "repent" for their past indifference to the AIDS crisis and for stigmatizing people with AIDS. She has built bridges between religious and secular relief groups, refusing to insist on abstinence or condoms as an either/or moral choice. With the proceeds from The Purpose Driven Life, the Warrens have now launched an ambitious global initiative to address crises such as poverty, illness, and illiteracy. Unlike the Evangelical leaders of previous years — even a Richard Cizik or a Jim Wallis, for example — Rick Warren says he is essentially uninterested in politics per se. He's interested instead in galvanizing churches themselves as forces for social change. But as his cross-cultural stature has grown, he has become a Billy Graham figure for a new generation, a pastor and spiritual advisor to powerful people — among them George W. Bush, Rupert Murdoch, and the leading candidates for president in the 2008 election on both sides of the partisan divide. He put Saddleback Church forward on August 16 as a force for a "civil forum on the presidency." Warren's format-breaking live audience of one hour consecutively with both Barack Obama and John McCain was aired live on CNN. This was, after all, their first time on the same stage as the presumptive candidates for president, on the cusp of the conventions and the formal debates. But it was roundly dismissed and/or parodied by many. I've vented some of my frustration about that on our blog. I'm glad we have this personal conversation with Rick and Kay Warren to return to, and put out there, to fill in some of the gaps of understanding and attention to nuance that too often appear when commentators and pundits generalize about Evangelicals — that is to say, some 40 percent of the U.S. population. Whatever anyone may think about Rick Warren's theology or personality, it behooves us to understand him. He is a global force to be reckoned with in the period to come. And he will have the ear of whomever moves into the White House next January.