“We have all these huge issues, and we’re bogged down in whether Joe can marry Bob.” Gay marriage has gone from an abomination to a diversion.

The charge is not new. Democrats have long accused Republicans of exploiting “social issues” to play to their evangelical base – and so giving the party’s real powers the cover to dismantle the welfare state. Indeed, I have done that myself. Republicans, by contrast, now assail Democrats for playing the gay card to deflect attention from the economy.

But gay marriage is not a tangential matter. It is a defining issue of today’s politics. It is part of the ongoing struggle for America’s soul.

As a country we are at our best when we expand the rights of people. Those efforts have never come without fierce opposition – from the mid-19^th century when a tiny group of abolitionists were dismissed as fanatics to the mockery of suffragettes to the murder of civil rights activists. And marriage has long been a focal point. When I was a child, it was a mortal sin for a Catholic to enter a Protestant church, let alone get married in one, and it was not until 1967 that a unanimous Supreme Court declared Virginia’s ban on interracial marriage unconstitutional.

When I ran for Congress in 1996, my position on gay marriage was “evolving.” I knew the right answer. I was just too chicken to give it. It’s a lot easier to stand up now, but it is not too late.