I heard Rick Warren talking on National Public Radio the other day.

Warren is the author of the mega-best seller, The Purpose Driven Life, the founder and pastor of the 22,000-member of Saddleback Community Church in southern California and soon will host the first joint appearance of Barack Obama and John McCain in the presidential campaign.

What caught my attention is Warren's description of the changing nature of political involvement by evangelical Christians - the group of voters who have been part of the powerhouse behind the Reagan revolution and more recently, the election and re-election of George W. Bush.

The thing is, Warren is not part of the old-guard leadership of the Religious Right. They really are fading from the scene. He is in the forefront of this era's evangelical leaders.

The typical boxes those of us on the liberal side of the equation tend to put evangelicals into come in two shapes. One pits evangelicals as the enemy -- narrow-minded, focused almost entirely on abortion, gay marriage and perhaps, at the edges, a vehement rejection of evolution.  A second thinks of a new generation of evangelicals as liberal allies -- stepping past the narrow issues of their predecessors and caring more about poverty and AIDS and global warming.

There's of course an element of reality around both of those boxes, but they really are too simplistic. And that's where I found Warren's words helpful, both in thinking about modern evangelical Christians and their impact on the 2008 election.

When NPR's Melissa Block asked him about the perceived split between older and younger evangelical voters, he replied: "I'm spending almost all my time with the next generation of evangelicals. What I've seen is that they are broadening the agenda. But they're not dropping the agenda. That is the biggest myth and wish that some people would like to see happen, but it isn't happening."

In other words, capturing the evangelical vote -- particularly the younger evangelical vote -- is not a slam dunk for either Obama or McCain.  That's one of the things that will make the Aug. 16 forum at Warren's church so interesting.

A footnote about Warren himself that I find fascinating and reflective of the greater openness among evangelicals today. NPR's Block reminded him that in 2004, he sent out a letter to pastors describing his five "non-negotiable" issues: abortion, gay marriage, human cloning, stem-cell research and euthanasia. She asked if that was still his list.

Consider these excerpts from his answer: "Well, they might be for me. It doesn't necessarily mean they're for everybody in the nation. I have my own convictions, but I also believe in the common good. I think that's part of democracy. You have a right to promote whatever view you hold, and you have a right to try to convince me that I ought to change my mind...

"On a personal level, if I were sending out a letter today, my view hasn't changed one bit on any of those particular subjects. But my agenda has expanded dramatically over the last four years. And I think one of the things I've tried to do with evangelicals is to get them to not deny their pre-existing agenda but to expand it.

"I'm still pro-life, but I don't call myself pro-life anymore. What I do is call myself 'whole-life.' I'm not just in favor of the unborn baby. I'm in favor of her when she's born. Is she a crack baby? Is she an AIDS baby? Is she a baby living in poverty? Is she going to get an education? It's not just concern for protection of the unborn but for protection of the born, too."

It strikes me that there is room there for folks on the liberal side of the spectrum to find some space to work together with conservative evangelicals on some issues, even if they disagree on others. That's a huge and welcome change over the last decade, moving beyond the demonizing that has characterized so much of the political and religious warfare in the public arena.