I frequently hear Christians claim that the United States is a Christian nation, or that the Founding Fathers intended us to be a Christian nation. When they bother to offer evidence it's usually some McCarthy-era addition to our pledge or our money, or some quote (often bogus) from a speech or a letter by one of the Founding Fathers.
Think about this for a second: If you were starting a Christian nation, how would you go about it? Would you make oblique references to "Great Powers" and "Guiding Hands" in obscure speeches and letters, or would you fill your foundational documents with references to Jesus Christ and the Bible?
The Founding Fathers were brilliant men. They spent months and months working on the Constitution. They were very, very careful about what they wrote, discussing and debating every passage at great length. It seems to me that if they had intended this to be a Christian nation they would have said so somewhere in the Constitution. The Founding Fathers had no reason to be vague. There was no ACLU, no "Activist judges." If they had wanted a Christian Nation they could have written:
God Almighty, in Order to form a true Christian Nation, establish Divine Justice, insure adherence to His Laws, provide for the defense of His Church, promote His Word, and secure His Blessings of Liberty to ourselves and our Posterity, has led us to ordain and establish this Constitution for the United States of America.
Instead they wrote:
We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.
The words "Jesus" "Christ" "Bible" "God" and even "Creator" appear nowhere in the Constitution ("Endowed by their Creator" is in the Declaration of Independence.) Just how stupid would someone have to be to create a Christian nation then forget to mention Christ in the Constitution?
Also notice that nobody ever asks what the Founding Mothers might have said. There were no Founding Mothers. The Founders were all men; White men, many of them slave owners. White male slave owners who may or may not have been Christians, but explicitly forbade any kind of religious test for office. In other words, you have a far stronger case if you'd like to argue that the Founding Fathers intended us to be a racist and sexist nation.
I think you can make a good case that some or even most of the Founding Fathers were Christians, but it's absurd to think that they wanted to impose that belief on the nation, and even more absurd to imagine we should be bound by their prejudices.