As this interview with Greta Van Susteren shows, as Newt Gingrich gets closer to announcing a bid for the presidency, an old issue is being given new life — namely, how relevant is marital infidelity when it comes to choosing a president?

On one end of the spectrum are those who believe the issue is dispositive; infidelity is a show-stopper. The argument is that a person who betrays his spouse cannot be counted on not to betray any principle or any vow, including one to defend the Constitution. No one would deny that unfaithfulness and sexual indiscipline bear on character, and character matters. “Betrayal is a garment without seams,” in the words of Professor Robert King. Serial infidelity in particular is a sign of a deeper disorder, having to do with narcissism, compulsiveness, and feelings of invulnerability. And whether we like it or not, presidents are role models. How they conduct themselves matters.

For others, infidelity by a politician is a matter of indifference. We elect a president, not a preacher, and while infidelity may be a troubling personal characteristic, it has little bearing on a person’s public duties. Many able public officials have also been philanderers. “Libido and leadership” are linked, Eleanor Clift argued during the Clinton years. There are plenty of sins that are considered problematic in the Hebrew Bible and the New Testament; why focus on infidelity instead of, say, self-righteousness? And of course a person who cheats on his spouse might also embody virtues in other arenas (for example, battlefield valor). If the choice during World War II had been between an unfaithful Winston Churchill and a faithful Neville Chamberlain, who would you rather have had as prime minister?

Many of the rest of us are on a continuum when it comes to deciding how much infidelity should matter in the selection of a president. Facts and circumstances are crucial. Was the infidelity an isolated instance or a chronic pattern? Were the transgressions long ago or recent? What levels of deception and cover-up were involved? What was the position of authority the person held when the infidelity occurred? Was there an alarming degree of recklessness on display? What evidence is there that this person has changed his ways? Has this person shown other worrisome signs when it comes to character and trustworthiness?

These are not easy matters to sort through. Lives have moral trajectories. Before his conversion on the road to Damascus, Paul was a persecutor of Christians. Every saint has a past and every sinner has a future, in the words of Oscar Wilde. But not every sinner has the same past. Forgiveness shouldn’t be confused with what Dietrich Bonhoeffer called “cheap grace.” And when the situation allows for it, it probably makes sense to invest our trust in public officials whose lives have been characterized by integrity rather than by self-indulgence.