WASHINGTON -- When asked why they'd come to the National Mall on a recent overcast Saturday, four days before the Supreme Court would hold its latest hearing on same-sex marriage, nearly all of the dozens of people I talked to opened with the same statement, pretty much word for word: "I believe that God's marriage is between a man and a woman."

Several added, as an afterthought, "God made Adam and Eve, not Adam and Steve" -- looking at me frankly, as if that settled everything.

This is my third year reporting on the National Organization for Marriage's annual "March for Marriage." The past three years have not been kind to opponents of gay marriage in America, who have, with only minor exceptions, lost every significant legal, political and cultural battle they've fought. This year's march was billed by NOM President Brian Brown as "our last, best opportunity to reach the U.S. Supreme Court before they decide whether marriage as it has existed throughout our history is unconstitutional." But nearly everyone I talked to said they felt that moment had already passed.

"Honestly, I think it might be over," said Mary, a 27-year-old woman from Virginia who declined to give her last name.

Nearby, two women in long dresses and sun hats were talking about the end of days. "It's like my daddy always says, we're going to hell in a handbasket," said Jaime Smathers, 37, who'd come with her church from Virginia. She didn't smile as she said it. There is very little joking at the March for Marriage.

"We are decades behind in explaining the benefits of marriage to the American people," said Michael Drake, a clean-cut, intensely somber man wearing the red sash of the American Society for Defense of Tradition, Family and Property -- a conservative Catholic organization whose members have described natural disasters as "God's chastisement" for legalizing same-sex marriage.

On the stage behind us, Carlos Luis Vargas Silva, the founder and president of a group called Centro Biblico Internacional, revved up the crowd. "God didn't do Adam and Steve, he did Adam and Eve!" he shouted, to wild cheers and shouts of "praise Jesus." "Our planet is going to suffer," he continued. More cheering.

If you want to talk to someone who believes that gay marriage will bring about the apocalypse, destroy the "fabric of humanity" and lead to elementary school children learning about fisting, as two very sweet older women told me last year, the March for Marriage is the place to be. But don't expect to hear many arguments that don't involve the wrath of God.

I asked Drake if he could explain to me, in secular terms, why the United States government should not recognize same-sex marriage.

"Marriage predates the Bible. It's always existed. It's nature, it's biology -- a man, a woman," Drake told me, looking wistfully into the crowd of thousands of like-minded protesters. "Sadly, we frequently delude ourselves about things that should be obvious."

In Drake's view, secular Americans -- and the American media in particular -- are the ones ignoring the tough questions. "Why stop at two people?" he asked. "Why not five people, if it's just about love?"

"Children need a mother and a father," said Margaret Benise, a woman from Maryland, as her three children sat quietly on the lawn beside her. What about those tens of thousands of children already living with same-sex parents? "They should try their best to find their fathers," she said, adding, almost under her breath, "We can't solve every problem at once."

One problem often alluded to at events like this is the issue of, as they say, "unwanted same-sex attractions." As one speaker after another took the microphone, warning that Christians were under attack and urging the crowd to keep up the fight no matter what the court ended up doing, a soft-spoken man approached me with a shy smile. He wore a billboard reading "The Art of Marriage," and invited me to attend an upcoming ex-gay banquet. "I can't tell you where or when it is, because they don't want protesters to come," he said. "But if you are interested, I can try to get you an invitation."

His billboard proclaimed that marriage "is not just marrying the right person, it is being the person of Biblical faith for your family." I asked him if he was ex-gay himself. He cocked his head and stared at me. After a long pause, he said only, "I have attended two of the banquets."

A decade ago, a majority of Americans, like those gathered on the mall on Saturday, believed that same-sex marriage was wrong. Today, the holdouts seem bewildered that the rest of society has moved on without them. If only they could convincingly explain why gay marriage will harm society, maybe things wouldn't be so bleak for them right now. Andrew Cuff, 26, a graduate student studying medieval philosophy at the Catholic University of America, attempted the task. "I'm a married human being, so what does this mean for me?" he said. "It's against the way I see marriage. It's against the way I see myself." Same-sex marriage is wrong because, well... because it's wrong.

The Supreme Court seems unlikely to be swayed by such reasoning. Back in 2013, while striking down the federal government's ban on recognizing same-sex marriage, Justice Anthony Kennedy wrote that the ban served "no legitimate purpose" and was motivated by a desire to harm gay and lesbian couples and their families.

The people who attended Saturday's event will no doubt continue to show up at similar functions for years to come, regardless of what the Supreme Court rules this summer and how the majority of Americans now feel. In fact, I got the sense that most of the people at NOM's march this weekend weren't really there to influence the court. Rather, they'd come to take a religious stand in a world that they feel increasingly devalues religion.

"It made me feel a little less isolated," Benise told me, of the rally. "Some days you really feel like you're on your own."