Two hundred and twenty-two years ago, as a Virginia legislator, he prepared to do battle against Patrick Henry's proposal that the newly independent Virginia commonwealth pay public teachers of Christianity out of tax revenues. The problem, Madison realized, was that if the law passed, it was bound for court, where a judge would then have to sort out just what it was that might constitute "authentic" Christian belief and practice.

Madison lived in an overwhelmingly Protestant state, but he well knew that when it came to issues ranging from baptism to church governance to liturgy, highly important differences existed among Anglicans, Presbyterians, Baptists and Quakers. We ought to count ourselves eternally in his debt that his arguments on behalf of religious freedom prevailed.

The landscape Madison surveyed in post-Revolutionary America is far more diverse today. When researchers at the City University of New York's Graduate Center asked Americans to describe their religious identity five years ago, slightly more than 75 percent said they were Christians. But then it got interesting: those people gave the researchers more than 30 different major Christian identities: Roman Catholic to Mormon to Jehovah's Witness to Pentecostal and many others. To say the obvious, not all these groups necessarily recognize each other as possessing Christian truth, in whole or in part. Even in an ecumenical age, differences count--often a lot.

And what about that other quarter of the population that doesn't identify itself as Christian? Well, it is very diverse religiously... and it is growing.

A "Christian nation?" Better to say we're a nation with a very large number of people who begin by identifying themselves as Christian, and then go from there.