Romney's challenge, however, is to make this clear to the American public. It is here that the parallel to Catholicism is instructive.

John F. Kennedy was not the first Catholic to run for president. That distinction belongs to Gov. Al Smith, D-N.Y., who, after winning the Democratic nomination in 1928, faced outright hostility to his Catholicism and suffered an ignominious defeat at the polls. The anti-Catholic bigotry that Smith confronted was in the living memory of many Democrats as Kennedy began his bid for the presidency. In an era when primaries were nonbinding and often ignored by the leading candidates, Kennedy entered the West Virginia primary to show that a Catholic could win in a heavily Baptist state and thus settle the "Catholic question." He won the primary and the nomination. But still doubts lingered in the minds of the electorate about his religion.

To put those doubts to rest, Kennedy marched into the proverbial lion's den and delivered a speech to Protestant ministers in Houston. That speech is a classic appeal for religious tolerance. In it, Kennedy declared, "I do not speak for my church on public matters, and the church does not speak for me."

Similarly, enough Americans have doubts about Romney's religion that he should not wait for the primaries to tackle the "Mormon question." Recent polls find that about four out of 10 Americans say that they are unwilling to vote for a Mormon. We suspect that many voters are simply reflecting the fact that Mormonism is unfamiliar to them; it is natural to be uneasy with the unknown. However, Romney's own election in Massachusetts as well as the elections of Gordon Smith, Rep. Ernest Istook, R-Okla., and former U.S. Rep. Richard Swett, D-N.H., demonstrate that voters outside the Mountain West, where Mormons are most heavily concentrated, can become comfortable with Mormon candidates from across the political spectrum.

Making his case — now

The heavy scrutiny focused on presidential candidates, even this early in the campaign, and the unease of some voters with a Mormon president, means that Romney should do now what Kennedy waited until the fall of 1960 to do. Romney needs to take a page from the Kennedy playbook and address his religion forthrightly, in a high-profile venue.

At a time when religion and politics are increasingly intertwined, it would be an opportunity to remind all Americans why the wall between church and state has served the country well.