Warren, 70, really is a grandpa. Born on an Iowa farm, he's quick with a down-home hug and a smile. His pale blue eyes grow misty when he speaks of his love for his wife of 46 years, Marylyn, the senior vice president at eHarmony.

And he really does want to set you up — but only if you're emotionally healthy, heterosexual and want to get married.

A psychologist with a divinity degree, Warren has emerged from the Christian community — three of his 10 books on love and dating were published by conservative Focus on the Family — to become one of the Internet's most unlikely entrepreneurs.

His secular matchmaking service has grown into the fourth-largest dating site on the Web, behind Match.com, Yahoo and Spark Networks, according to Internet measurement company comScore Media Metrix. Later this summer he plans to announce an online service aimed at assessing and improving marriages.

The connection may come as a surprise to today's mainstream users: Nothing in Warren's TV or radio ads ($50 million spent last year, $80 million projected this year) hints at his Christian background.

And while it's no secret, the Web site doesn't play it up, either.

eHarmony increasingly is seeking out secular audiences through online partnerships, including promotions on USATODAY.com and other news sites owned by USA Today's parent company, Gannett. As part of that effort, Warren is trying to distance himself from Focus on the Family and its founder James Dobson, a longtime friend.

Warren says he will no longer appear on Dobson's radio show, and he recently bought back the rights to the three books Focus on the Family published — "Finding the Love of Your Life," "Make Anger Your Ally" and "Learning to Live With the Love of Your Life " — so he can drop Focus' name from their covers.

"We're trying to reach the whole world — people of all spiritual orientations, all political philosophies, all racial backgrounds," Warren says. "And if indeed, we have Focus on the Family on the top of our books, it is a killer. Because people do recognize them as occupying a very precise political position in this society and a very precise spiritual position."

Says Andrea Orr, author of "Meeting, Mating, and Cheating: Sex, Love, and the New World of Online Dating," "He has this evangelical Christian background, but I know plenty of Jews who use the site, and I don't really see the evangelical Christian background coming through.

"I see a strong sense of morals and a sort of conservatism. But I don't find it very much in-your-face at all. It's more sort of this grandfatherly moral thing."

While other leading dating sites allow users to find their own matches by searching through online ads, eHarmony has people fill out a 436-question test designed to evoke thoughtful and revealing responses. eHarmony then sends potential matches, encouraging people to get acquainted before they even see each other's photos.

"We do try to give people what they need, rather than just what they want," Warren says.

"There's a way in which, a little paternalistically, we say we have discovered, on the basis of our research, what is required to make a marriage great. And we're going to help with that. Our way."

Most dating sites have various payment systems; usually they lure daters in with something free, such as personal ads, and then charge when daters want to start communicating with matches.

Of the leading dating sites, eHarmony is the most expensive, starting at $49.95 a month. Match begins at $29.99, Yahoo at $19.95. Spark Network's largest site, American Singles, starts at $34.95.

But at least 7.5 million people have registered to take eHarmony's test, which is free. Users must pay to get contact information for matches. The site, which is privately held, does not disclose the number of paying members.

"You tend to meet more marriage-minded people there," Orr says. Still, "online dating is a little bit of a crapshoot, no matter which site you use. I've talked to people who've used eHarmony who were matched with people who really didn't do the questionnaire very thoughtfully."

But others swear by it.

Maura Lockwood, 29, of Plattsburgh, N.Y., says she followed up on only one match from eHarmony, and he turned out to be the one. She was matched with Joe Alix, 30, on July 19, 2003. By the time they met in person two months later, they had spoken and e-mailed so much that "I knew I loved him before I met him," she says.

Their wedding is planned for Aug. 20. Warren suggests couples wait two years to tie the knot.

Not everyone agrees with his advice. Warren recommends against premarital sex because it can "cloud decisions." Lockwood moved in with her fiance right after Thanksgiving.

Some also criticize eHarmony's decision to refuse to provide matches for gays and lesbians, a policy that differs from Yahoo, Match.com and many other sites.

"From a corporate perspective, eHarmony does discriminate. There's clearly a deliberate desire to exclude gay people from the site," says New York psychiatrist Jack Drescher, who is gay and treats gay and lesbian couples.

Warren says eHarmony promotes heterosexual marriage, about which he has done extensive research. He says he does not know enough about gay and lesbian relationships to do same-sex matching.

It "calls for some very careful thinking. Very careful research." He adds that same-sex marriage is illegal in most states. "We don't really want to participate in something that's illegal."

Lesbians and gays are not the only ones unwelcome on eHarmony; Warren says he rejects 16 percent of those who take his patented personality test because they're poor marriage prospects.

Weed-outs include people under eHarmony's 21-year-old age limit and those whom the site decides are lying on the test. It also removes those believed to have certain types of emotional instability, such as "obstreperousness" (they just can't be pleased) and depression, because "depression is pretty highly correlated with emotional problems," Warren says.

"You'd like to have as healthy people as you can. We get some people who are pretty unhealthy. And if you could filter them out, it would be great. We try hard. And it's very costly."

But eHarmony does not reject on the basis of religion; it has atheists, agnostics and even Wiccans among customers, he says.

Warren says he's not lukewarm about his own faith.

"I am a passionate believer," he says, sitting in the quiet eHarmony headquarters, his former therapy office, lined with bookshelves holding "The Joy of Sex," volumes of Freud and everything in between.

But he says his religious beliefs are grounded in humanism and psychology, and he often intertwines the two. "I think there is something very incredible about Jesus. I don't back away from that. At the same time ... the public we want to serve is the world.

"You can say that that is just a good business idea, because it increases the size of your market. But it's also for me a philosophical point: I think our world will be a lot better world if we can help people of all types get married well."

29 key traits

Matches on eHarmony are based on "29 areas of compatibility" developed Warren.

A marriage will likely thrive if couples share at least 10 of these key personality traits and habits, from curiosity and industriousness to ambition, traditionalism and feelings about children, Warren says.