Forgive me, Lord, for I have sinned: I cheated on my wife. I brought shame and dishonor to her, and to my children. But I have asked them to forgive me.

And now I’m asking voters to forgive me, too.

Welcome to our political culture of sexual confession. Pioneered by Bill Clinton, who groveled on TV after his affair with Monica Lewinsky was exposed, confession has become an invaluable weapon for leaders who are caught with their proverbial pants down.

Witness the fates of Clinton’s fellow Southerners David Vitter and Mark Sanford. Vitter won re-election to his Louisiana Senate seat in 2010 after admitting a “serious sin” involving prostitutes. Earlier this year, former South Carolina Gov. Sanford captured a House seat after acknowledging an extramarital affair.

In New York, meanwhile, Anthony Weiner and Eliot Spitzer are trying to pull off the same stunt. Forced to resign from Congress when his racy tweets to women came to light, Weiner is the frontrunning candidate for mayor in some polls. And Spitzer recently announced his bid to become city controller, despite a prostitution scandal that pushed him out of the the governor’s office....