The enduring argument over the role and limits of faith in public life is one of the thirteen I identify and explain in the book. We are uniquely born and bred to argue. That we do – that we MUST – is a blessing rather than a burden. It’s how we nurture freedom and progress.

We have no official religion, of course – that was one reason why we fought a revolution – and yet we are one of the most prayerful nations on earth. We see little distinction between the idioms and icons of faith and politics. Presidential candidates’ religious beliefs – or lack of them – have been topics of debate since Jefferson’s day.

Presidential elections are about character and a candidate’s faith outlook is evidence. We are a tolerant people, as the latest Pew Survey reminds us: more than two thirds of us think that their own religion is not the only route to eternal salvation. But we still like to know what role faith plays in the lives of those who would lead us.

So it goes in this election season. In the primaries, the role of Mormonism in Mitt Romney’s political life generated front-page news, as did Barack Obama’s now-abandoned membership in Chicago’s Trinity United Church of Christ. As the general election race heats up, Republican strategists wonder aloud whether McCain should choose as his running mate Gov. Tim Pawlenty of Minnesota, whose prime qualification seems that he is an active, well-connected evangelical Christian. Dr. James Dobson has declared that he would never vote for McCain, and many other evangelicals remain skeptical – and eager to advertise their skepticism.

As in everything else about this cycle, the central figure is Obama, who is not only breaking racial barriers, but challenging religious ones. The latter may be more problematic in the end. His blended family heritages help him connect with younger, tolerant voters, who regard him as a cool, cutting edge symbol of hope and generational change. And yet the very fact that he has assembled himself from many parts raises suspicion among voters who see faith and race in immutable terms.

Only in America, and in an American political race, could a Jewish mayor from New York make news by vouching for the Christian faith of a candidate whose long-dead father was a Muslim. But that’s what happened in Baca Raton, Fla., the other day, when Michael Bloomberg reassured a Jewish audience that Obama was a Christian.

But what kind of Christian? That is a question Obama and his campaign know that they must try to answer, and answer in a reassuring way. His campaign is reaching out aggressively to evangelicals, and even proposed a meeting with Dobson.

In a preemptive rejection of that feeler, Dobson took to the airwaves this week to denounce a 2006 speech Obama gave to a Christian group in 2006, in which the then not-quite candidate stressed the social gospel and peace teachings of the New Testament. Obama, said Dobson on his “Focus on the Family” radio show, is “deliberately distorting the traditional understanding of the Bible to fit his own worldview, his own confused theology. He is dragging biblical understanding through the gutter.”

Strong words, of course, but hardly unprecedented in our history. Whatever Thomas Jefferson’s beliefs, they weren’t traditional enough to satisfy his Federalist critics. In the tumultuous election of 1800, he was branded an atheist or worse, and one Federalist newspaper asked the question: Did its readers want “GOD—AND A RELIGIOUS PRESIDENT; OR JEFFERSON—AND NO GOD!!”

We got Jefferson, and we still have God.

Howard Fineman is Newsweek's senior Washington Correspondent and columnist, senior editor and deputy Washington Bureau Chief. He is also the author of "Living Politics," a column that began and continues on MSNBC.com and Newsweek.com and is now featured in the print magazine. Read an excerpt from his new book, "The Thirteen American Arguments."