If you want to know why social conservatives have effectively lost the battle over same-sex marriage with the American people, you need look no further than former senator and now Heritage Foundation president Jim DeMint.

Jim DeMint Jim DeMint, president of the Heritage Foundation. (Evan Vucci / AP Photo)

On “Meet the Press,” he said the following:

What I’d say, David, is [Justice Kennedy] is denying dignity to the millions of Americans who, for moral or religious reasons, believe that gay marriage is wrong. As you just said, you’ve got 37 states where the people have decided that they want to protect the marriage between a man and a woman because they know that that’s the environment where children can thrive and succeed. I mean, that’s been proven.

So it’s not about the desires of adults, it’s really about the best environment for children. We’re talking all about politics, but the reason governments at the state level and the federal level have recognized marriage between a man and a woman is because it’s better for our country and it’s better for children.

It’s hard to know where to start. Kennedy’s opinion didn’t deny people the right to have a “traditional” marriage definition; it says the law can’t deny to others who want to recognize same-sex marriage the right to do so. This is the essence of tolerance — living with others’ whose views you dislike or even offend you. It makes social conservatives out to be small-minded to suggest they cannot abide by states that democratically make different decisions than they would prefer.

The 37 states DeMint is concerned about, for now, can keep their traditional marriage definition — unless their residents decide otherwise. But he better come up with more persuasive reasons if he wants those states to stop expanding the definition of marriage.

His regard for “the children” reeks of Rep. Nancy Pelosi (D-Calif.) at her worst, using children to justify her particular policy preferences. Of course, lots of things are bad for kids, including divorce. Do we ban that? Moreover, not all couples have children (by choice or otherwise). And finally his notion that this has all been “proven” is simply wrong.

On one level, it is shocking that a once highly regarded think tank should have a leader whose arguments are so intellectually flabby. But on the other hand, if the crown jewel think tank of the hard right and their darling DeMint can’t make a cogent argument, maybe there simply isn’t one.

From the center-left Brookings Institution we get a more reasoned analysis of marriage’s effect on “the children”:

Children living with single parents do worse than children living with their married parents. There is now widespread agreement that children living with single mothers are more likely to do poorly in school, to be arrested, to have a teen birth, to have mental health problems, and to go on welfare as adults. They are also four or five times more likely than children living with their married parents to be in poverty. It is one thing for adults to make choices that jumble tradition, but children do not get choices about the composition of their family.

If the trends reviewed here continue, many more children will live in poverty and the development of a substantial fraction of the nation’s children will be disrupted, with consequences for individual children, their parents, the economy, and society. The nation should continue exploring ways to increase marriage rates and reduce nonmarital birth rates.

We’d do much more for “the children” if we worked on preserving two-parent families than inveighing against adults who want to get married.

If the anti-gay-marriage forces are reduced to arguing that they have a right to prevent other states from choosing a more-expansive definition of marriage because it offends their religious sensibilities, the pro-gay-marriage forces don’t have much work to do. Americans are instinctively tolerant people — even if they don’t subscribe to others’ choices. That is the essence of the First Amendment and of free people — we allow diverse choices.

Ironically, the best proof of this comes from a very religious couple. The Post features the story of a wedding in Alabama:

“For Randy and me, marriage is about our commitment to each other as one man and one wife,” Amanda Joy, who prefers to be called A.J., had said before the wedding. “Even with the decision of the Supreme Court, for us, this union is just a picture of the love God has for us. And to explain that to the world as a husband and wife, that is our heart.”

Their marriage was no less precious after the Defense of Marriage Act case than before, just as thousands of heterosexual marriages entered into after states began to expand the marriage definition were not less special than marriages before states took that step. That seems perfectly clear to those who still embrace a traditional view of marriage:

“What’s happening is not going to change what we believe,” said Dee, who declined to have her last name used because of family sensitivities. She said the issue was personal since she has a close relative who is gay. “I had family members who wouldn’t let him in the house, and I said, ‘No, no, no, we love you, we are not going to let this issue come between us.’ Spiritually we are polar opposites, but I love him. So, I mean, yeah. This is who we are and what we believe, and I think it is important to have conversations.” . . .

Brynn Marcum, 23, married two years to her husband, Zach, said that her generation is less threatened by same-sex marriage than her parents were, though she is no less committed to what she considers the same Christian values.

“We are not going to go picket against gay marriage,” she said. “We are going to bring the example to people by who we are.”

I think she’s got it.

Anti-gay-marriage advocates seem to have blurred the division between civil and religious marriage. Churches and synagogues can do as they please in adhering to traditional marriage; individuals can retain their own beliefs as to an ideal marriage, but the state in a pluralistic society allows others to make different choices. And in our federalist system we allow states to make different choices as well.

Unfortunately, Kennedy entirely confused the matter by mixing 10th Amendment with 14th Amendment language. If social conservatives want to be strategic, they should do what they were denied the opportunity to do after Roe v. Wade — make their case around the country to state legislatures. In some places that won’t be hard, but in others state legislatures will regard DeMint’s arguments as flimsy.