Elahe Izadi runs down the well-documented efforts of Our Founding Fathers Themselves to ensure that yes, religious freedom even extended to Jews and "pagans" and Muslims.
So unlike Jews and Catholics, Muslims were discussed in the hypothetical — and often with negative opinions, including those held by Thomas Jefferson — to show "how far tolerance and equal civil rights extends," said Denise Spellberg, author of "Thomas Jefferson's Qur'an: Islam and the Founders."
"In the formation of the American ideal and principles of what we consider to be exceptional American values, Muslims were, at the beginning, the litmus test for whether the reach of American constitutional principles would include every believer, every kind, or not," Spellberg said in an interview.
Ending collusion between the state and any state-preferred religion was not just Jefferson's own objective, but the stance that would be codified in law and in the Constitution. There are ample writings to prove that non-Christian religions were specifically intended to be protected, and anyone who has the slightest intellectual interest in the American version of freedom of religion has read through them already. A few were in my old high school history textbook—but that was back in Ye Olden Days, so I have no knowledge of whether such quotes and letters have been scrubbed by the forces of Texas Jeebus, in the books your own offspring are thumbing through today.
The point is, there's simply no way to claim you know either the Constitution or what America's religious freedom was intended to "mean" unless you are aware of Jefferson's own efforts to ensure sweeping inclusivity and that Jefferson was not operating in an intellectual vacuum but from a broader intellectual and legal movement to do that thing, both within the states and when the time came to piece together the national version people now carry in their shirt pockets.
Unfortunately, this doesn't itself make a whole lot of difference; Constitution-enshrined religious freedom extending to the non-Jesus religious is now considered among prominent conservatives to be the history-book version of a climate change conspiracy. Glenn Beck has found himself his own self-proclaimed history guy to explain why all the other historians are wrong; those that disagree are merely part of a larger modern plot to something-something Muslim guy marrying your daughter. But from an actual, historical standpoint, all this was hashed out a quarter millennium ago using very similar arguments and in the midst of very similar prejudices, and we generally accept that the "good guys" won.
At least, most of us do.