Award-winning journalist Ray Suarez was paying respects to a Founding Father when I called him Memorial Day.

"I'm out for the holiday in Philadelphia. So I'm standing over Benjamin Franklin's grave. I excused myself, walked away," he said laughing "Now I'm standing out in a bunch of gravestones."

The alum of NPR's "Talk of the Nation" and PBS' "NewsHour," laughed when I thanked him for the imagery.

An author whose books include "The Holy Vote: The Politics of Faith in America" is in the metro Thursday to speak at the Interfaith Action of Greater Saint Paul Annual Assembly about "Who Will Be in the Pews in 2040?" The 7 p.m. St. Paul College event, open to anybody who pays $10, will be broadcast at a later date on MPR.

Churches are in crises, Suarez told me. It's a topic he sometimes gets to hash over with his daughter, the Rev. Eva Suarez, an Episcopal priest in the denomination in which her father raised all his children, all of whom are churchgoers.

Q: How can churches attract younger congregants without alienating the longer-term members?

A: That is THE question that's going to dominate internal debates, not only in individual congregations, but in denominations for the rest of the century. Apparently young people don't want what they're [churches] offering. So they either have to offer something different or be at peace with a demographic collapse.

It's not a trivial matter. The post-1965 religious growth has come because of the 1965 Immigration and Nationality Act, which brought Asian, Latin Americans, Africans in large numbers for the first time. So Islam, Hinduism, Sikhism and Spanish-speaking Catholicism started to zoom after '65. Those entities will have these challenges as well as their families continue their American journey and integration into American life. It will be on a slightly different timeline but their highly educated children and grandchildren will have the same sort of questions [as] today's young adults who belong to religions that have been in the United States longer.

As I try to break this down, yes, there are going to be differences between mainline Protestants and Jews and Hindus, but by the end of the century, unless they answer some pretty fundamental questions about prayer and liturgy and theology it's [laugh] going to be a really rough century. We're 19 years in, and this could be the end of some American churches.

Q: Does what you just said give people who want to keep America as white as possible another reason to keep out immigrants with skin tone?

A: Well yeah. We had a Chinese Exclusion Act on the books, which specifically said nobody from China could move to the United States and become a citizen. [Long laughs] How much more clear could you get from that? John C. Calhoun, when responding to people who wanted the United States to buy Cuba from Spain said, Look, we can't buy Cuba because we can't add all those mixed race people to the population; people of unclear racial status. Because he came from a world that was binary — you were either white or you weren't. We've had echos of this throughout American history. When we rewrote the immigration laws in the 1920s, they were formulated by Congress to reflect the foreign born-population of the country in 1890 ... before a lot of Italians and Romanians and Eastern European Jews came. So yeah, we've always been racially conscious about who belongs.

Q: The Constitution states that government should have no involvement in religion. Your answer to that first question also sounds as if future generations will remove religion from politics?

A: Again, there are some interesting wrinkles. The gist of what you said is absolutely right on. I don't think you are going to be able to run a campaign like George W. Bush [did] in 2000 by 2032 when a significantly larger part of the population will have no congregational affiliation, no religious upbringing, no faith home. Having someone quietly pepper speeches with Bible verses is going to be, "What's the point?" A smaller share of the population will be open to that kind of appeal.

Yeah, it's an open question whether you will be successfully able to do politics the way more religiously inclined candidates have. The numbers would suggest no. Young Americans, who are the largest single portion of the unaffiliated population, will probably continue to grow when they're the biggest share of voters in the 2030s. They are not going to be so interested in fights over things we have been fighting about for the last 40 years. Certainly not prayer in schools, things like that.

Q: How often do you go to church?

A: Every week and sometimes more than that. My daughter is an Episcopal priest. She asked me "When I walk into the pulpit in the 2040s, the middle of my career" since she was just ordained the year before last "who's going to be sitting out there?" And I said "Maybe me, I hope me, and what you and your colleagues do in the next 20 years is going to have a lot to say about whether anybody's out there."

Q: I know Baptists (I am, for the record, a non-church-going Presbyterian) who quip that nothing's a sin in your denomination.

A: Weeeelllll, not quite. Lying about it is a bigger problem than [laughter] some of the things other people think are sins. So, be who you are.

Q: What did you think of MSNBC's Mike Viqueira ambush interviewing special counsel Robert Mueller outside St. John's Episcopal Church in D.C. on Easter Sunday?

A: Um, I know Mike. He's a terrific reporter, a stand up, decent guy. If Mueller was available to him in any other way, he wouldn't have done it. You know, Mueller's been around Washington long enough that he understands the score. If you came up to him in the middle of church that would have been horrifying, but [Viqueira] didn't' do that. Church was over, and he was getting in his car.

Q: Could you believe Mueller was flustered to the point of forgetting how to use the key fob to open his vehicle? (tinyurl.com/y2dn6t7p) That was priceless.

A: [Laughing] I think, as someone who's done that work for a long time; if somebody's in the zone, walking out of church, standing there on 16th Street, they are about to slide into a car and suddenly there's a TV camera, even if you are a longtime, polished, DC operator, it might be something that surprises you.

Q: We haven't met, but you eyeballed me in 2008 when the RNC gathered in St. Paul. I wandered into the PBS "NewsHour" area trying to get Gwen Ifill's attention for an interview. She never acknowledged me, but you had me under surveillance the entire time.

A: [Laugh] Well, you know public TV stars get so used to being fawned over by the public — like never -- [more laughter] you've got to take advantage. [Laughing]

C.J. can be reached at cj@startribune.com and seen on FOX 9's "Buzz." E-mailers, please state a subject; "Hello" does not count.