A good read, Defenders of the Faith by Roger Rosenblatt
http://www.sikhtimes.com/news_111284b.htmlAn excerpt which summarise the gist of the issue
"All this connects with the American debate on church vs. state in a fundamental way. Those who would like to see religion exert more control over government claim that the founding fathers wanted it that way. They are nearly right. People like Franklin, Washington, Jefferson and Madison sought to separate church and state so that no one sectarian God would ever bestride the land. Yet the founders wanted God somewhere in the picture, as a guide to national moral conduct. Thus arose the God of our civil religion. You've seen him. Big fellow. Flexible but no pushover. Spencer Tracy could have played him. His good book is the Constitution, his psalms were written by Walt Whitman, fair-minded citizens constitute his clergy.
What the founders did not want, however, was a country run on the bases of religion. America was born of the Age of Reason, so named not because people were more reasonable in the middle of the 18th century than at other times but because they set reason as the standard of human aspiration. 'What reason weaves, by passion is undone,' wrote Alexander Pope. Alexander Hamilton agreed, though warily: 'Men are rather reasoning than reasonable animals, for the most part governed by the impulse of passion.' It was one thing for individuals to be governed by emotions and another to assign such governance to a new country. Keeping church and state apart was a way of separating reason and passion, or reason and faith, another check and balance.
This is easier proposed than carried out, but it is worth the effort, since the premises of church and state are not merely opposed but actively antagonistic. Faith implies the refusal to accept any laws but God's. How can a government that relies on the perpetuation of its authority be compatible with an institution that takes dictates from invisible powers?"