AT A time when Americans are worried about their crippling political divisions, it is pleasing to report that two social scientists, Robert Putnam of Harvard University and David Campbell of the University of Notre Dame, have just written a book that examines a powerful source of American unity. Perhaps unexpectedly, the unifying force they focus on is religion.

America's religiosity has been extensively documented and should surprise no one. It is, Sarah Palin said in her own new book this week, “a prayerful country”. More than eight out of ten Americans say they belong to a religion. More Americans than Iranians (four out of ten) say they attend a religious service nearly once a week or more. What is a surprise—or should be, when you think about it in the way Messrs Putnam and Campbell have—is that religion in America is not more divisive. They argue in “American Grace” (Simon & Schuster) that religion gives Americans a sort of “civic glue, uniting rather than dividing”.

The unifying impact of religion would not be so puzzling in a country where people were pious but where there was only one dominant religion—Catholic Poland, say. Americans, by contrast, hold intense religious beliefs but belong to many different faiths and denominations. That should in theory produce an explosive combination. So why doesn't it?

There are the protections of the constitution, of course. But the authors put much of it down to Aunt Susan. Such is America's churning diversity that most Americans are intimately acquainted with people of other faiths. Aunt Susan may be a Methodist, and you a Jew, but you know that Aunt Susan deserves a place in heaven anyway. In fact, Susan does not have to be your aunt, because in addition to the Aunt Susan principle the authors have invented the My Friend Al principle. In this case you befriend Al because, say, of a shared interest in beekeeping, and later learn that he is an evangelical Christian. Having an evangelical Christian in your circle of friends makes you warmer than you were before to evangelical Christians. Not only that, befriending someone from another faith makes you warmer to other religions in general.

This is not just a hunch. Mr Putnam and Mr Campbell administered a questionnaire to a representative sample of thousands of Americans in the summer of 2006, and in the spring and summer of 2007 they went back to question the same people. Sure enough, those whose circles had became more religiously diverse in between the surveys expressed measurably more positive feelings towards other religions.

Is this web of interlocking personal relationships among people of many different faiths the secret transmission mechanism of religious tolerance in America? One happy feature of modern America is indeed that soaring interfaith marriages over the past century mean that the average person has a good many Aunt Susans. Roughly half of all married Americans today are married to someone who grew up in a different religion from their own. So it is little wonder that when the authors asked their subjects whether a person of a different faith from theirs could find salvation and go to heaven, almost nine out of ten said yes.

Three blemishes in paradise

Yet Mr Putnam and Mr Campbell are also careful not to claim too much. About a tenth of Americans are what they call “true believers” holding strong and inflexible views about morality and their own creed's exclusive pathway to heaven; Aunt Susan is not welcome in their company. Also worrying is the continuing “God gap” in politics: Americans who are more religious have become Republicans and the more secular have become Democrats. A final blemish on the picture of tolerance is that the circle of those who are tolerated is tightly drawn.

For example, even though nine out of ten Americans think that people of a different faith can get into heaven, a much smaller proportion think that a Mormon should get into the White House, as Mitt Romney discovered in his 2008 campaign to win the Republican presidential nomination. When the authors asked respondents to rank their feelings about other religions, the resulting scores were highly uneven. Almost everyone said they liked “mainline” Protestants, Jews and Catholics. Evangelical Protestants liked almost everyone else more than they were liked in return. Mormons liked everyone else, while almost everyone else (except Jews) disliked Mormons. And almost everyone disliked Muslims and Buddhists more than any other group.

Part of the problem for Muslims and Buddhists in America could be their small number: few Americans have a Muslim relation or a Buddhist friend. But since being few in number has not prevented Jews from eventually becoming the most popular religious group in the nation, this is not a good enough explanation on its own. Osama bin Laden did not help American Muslims by attacking America in Islam's name, but Mr Putnam and Mr Campbell believe another factor is at work: the fact that Muslims, Buddhists and Mormons do not have a place in what people have come to call America's Judeo-Christian framework. Tolerance of Jews and Christians only? That is not quite so impressive.

Worse, anti-Muslim feeling may be growing. In a recent survey the Public Religion Research Institute found that 45% of all Americans, and 67% of Republicans, agreed that the values of Islam were “at odds” with America's way of life. Two scholars from the Brookings Institution, E.J. Dionne and William Galston, worried aloud this month that divisions over Islam inside America may now be deeper than they were ten years ago. George Bush tamped down anti-Muslim feeling, but some of today's Republicans—Newt Gingrich, with his wild crusade against sharia, is a spectacular example—seem intent on stirring it up. What chance does Aunt Susan stand against the demagoguery of fear?





Economist.com/blogs/lexington