You'd be surprised. This is what Thomas Jefferson had to say in his autobiography regarding the Virginia Statute for Religious Freedom (which was a precursor to the First Amendment):
"The bill for establishing religious freedom, the principles of which had, to a certain degree, been enacted before, I had drawn in all the latitude of reason and right. It still met with opposition; but, with some mutilations in the preamble, it was finally passed; and a singular proposition proved that its protection of opinion was meant to be universal. Where the preamble declares, that coercion is a departure from the plan of the holy author of our religion, an amendment was proposed, by inserting the word "Jesus Christ," so that it should read, "a departure from the plan of Jesus Christ, the holy author of our religion;" the insertion was rejected by a great majority, in proof that they meant to comprehend, within the mantle of its protection, the Jew and the Gentile, the Christian and Mahometan, the Hindoo, and Infidel of every denomination."