We are by no means a Christian nation. John Adams said as much in the Treaty of Tripoli. There's a lot wrong with assuming that our founders were all of a mind about religion--which is exactly the reason to presume we are not founded on religious principles, but practical ones. There are ample statements from our founders that attest that freedom of religion was the only way to maintain an already-diverse religious population, Thomas Jefferson was proud enough of his religious freedom edict in Virginia that he had it made a part of his final epitaph.