In a treaty with Tripoli in 1796, which had as its main object obtaining protection for American ships from pirates, the following paragraph was included, in article 11….
“As the government of the United States of America is not in any sense founded on the Christian Religion, – as it has in itself no character of enmity against the laws, religion or tranquility of Muslims, – and as the said States never have entered into any war or act of hostility against any Muslim nation, it is declared by the parties that no pretext arising from religious opinions shall ever produce an interruption of the harmony existing between the two countries.” I have taken the liberty to change the word Mahotman to Muslim so the meaning would be clear to a 2019 audience.
Tripoli was indeed a Muslim nation and here the rulers of the U.S. were reassuring them that they would not try and impose Christianity on that nation. While there were certainly Christians among the Founding Fathers, there were also non-Christians as well, and our founding documents owed more to John Locke than they did to the Bible. And one of the great concerns of the Founding Fathers is that there be no official religion of the country, unlike what had been the case with various of the original colonies. This was a change to protect various forms of Christianity from government interference, so for example Quakers, as well as Baptists, or Methodists, or Catholics or Jews would be left in peace to follow their conscience in the matter of religion. The goal was not to protect the government from the church, but rather vice versa.
I bring this up because there has been and continues to be a lot of mythology about the U.S. always being a Christian nation, and while that has always been the dominate religion of the majority of Americans, that in itself does not make America a Christian nation. The Bible, for example, says nothing about democracy and quite a lot about kingdoms, nor does it say anything about a bill of rights. One would find it easier to extract a bill of ethical responsibilities from the Bible rather than a bill of rights. Furthermore, the main freedom the Bible talks about is freedom from sin not freedom to own guns, or freedom of speech and the like. The reason for constant and ongoing confusion about these things is because the American civic religion and Christianity have often been blended together or fused into an amalgam, leaving people confused.