As in Sanford's case, what matters to the Christian right is not so much the behavior of their leaders as the repentance they show after their fall from grace.
Google "Mark Sanford" and "hypocrite" and prepare to sort through some 53,000 results, many from liberal websites reveling in the story of yet another family-values Republican yielding to temptations of the flesh.
But liberal glee at such scandal will be short-lived if the left continues to misjudge conservatives' reaction to their fallen heroes.
When a Republican affair is exposed, the left seems to assume that the religious right, with the exacting moral standards it tends to laud, will have one less general leading its "pro family" brigade.
But practice shows us otherwise. While for Democrats, adultery often leads to ruined or constrained careers – think Gary Hart, Bill Clinton, Eliot Spitzer, John Edwards – Republican adulterers from Newt Gingrich to David Vitter have lived to see another political day, still championing their hard-line conservative positions.
Their survival isn't in spite of the GOP's evangelical base, but rather because of it. And while liberals tend to see continued support as hypocrisy from both the politician and his supporters, what matters to conservative Republicans is not so much the behavior of their leaders as the repentance they show after their fall from grace.
In the rambling announcement of his affair, Mr. Sanford said little about politics and a lot about his faith. At times he sounded like a preacher expounding on the nature of God's law, of self, and of sin.
Sanford's remarks drew little praise, categorized even by sympathetic sources as "disjointed" and "just plain bizarre." Kathleen Parker, a conservative columnist with little affection for the politics of the Christian right, evaluated his statement this way: "Spiritually, Sanford may have succeeded in checking off several acts of contrition. But politically he did everything wrong...."
But Ms. Parker, like Sanford's critics on the left, fails to understand the mechanics of Christian conservatism: By getting it spiritually right, Sanford is well on his way to getting it politically right.
Last summer, another scandal threatened to derail the Republicans' moral majority train. When Gov. Sarah Palin announced her teenage daughter, Bristol, was pregnant, many liberals mocked the hockey mom for having to face the consequences of her abstinence-only educational advocacy.
They also figured, wrongly, that the news would destroy the Alaskan governor's appeal with her evangelical base. Instead, the moment endeared Governor Palin (who has since announced her resignation) to evangelical supporters, who cared less about the pregnancy than about what Bristol decided to do about it. The teenager's decision to keep the baby and her promise, later unfulfilled, to get married redeemed her momentary lapse.
The left marveled at the political sleight of hand that turned teen pregnancy from a social scourge into a family-values virtue. But as America's most famous evangelical pastor, Rick Warren, has written: "The church is a hospital for sinners, not a hotel for saints." Evangelicals forgive their fallen politicians when they show repentance and do right; when they keep the baby, when they marry the father or mother, when they repair the broken marriage.
What we are witnessing is the culmination of "the personal is political," a philosophy pioneered by the left and perfected by the right. The stumbling block for liberals is their unfamiliarity with the "personal" of the Christian right.
Where the left sees hypocrisy, the evangelical right sees a millenniums-old story of fallen humanity and healing redemption. With a politically active religious right, that story matters not just in terms of theology but of practical politics.
Mr. Vitter, the staunch social conservative Republican senator from Louisiana who also frequented a Washington, D.C., madam, has already raised more than $2 million for his 2010 reelection bid. When Vitter's scandal broke, he declared he'd "received forgiveness from God and my wife."
It appears he has the forgiveness of deep-red Louisianians also. Polls indicate Vitter remains highly popular in the state, and most observers believe he'll win the 2010 race.
There's a lesson in Vitter's story for Sanford: Confess, repent, repair. Some of this is out of Sanford's hands, of course. His wife has said his political future was the least of her concerns. Her priority, she declared, was the restoration of her family.
If Sanford's marriage remains intact, he can emerge as yet another flawed – not hypocritical – sweetheart of religious conservatives.
For the left, the redemption of Vitter holds lessons as well.
First: Don't count Sanford out. Though the South Carolina Republican Party just voted to censure him for disappearing, the party did not call for his resignation. If Christian conservatives grant Sanford political redemption, the rest of the Republican Party will as well, and the governor could be a contender in 2012 or 2016.
And second: Understanding the role of redemption for the religious right isn't just a matter of getting the theology right. It is the only way for the left to realistically read the political landscape. Because for evangelical conservatives, the point isn't the fall. It's how the politician gets back up.
Nicole Hemmer is a former fellow at the Miller Center of Public Affairs and is writing a history of conservative media. Neil J. Young is a lecturer in history at Princeton University. He is writing a book on the origins of the religious right.