...one of the topics of history that isn't discussed much is the disestablishment of religion in America.

I recall a talk from Hitchens, part of a book tour. He asserted that the USA was the first nation not to have an official religion. All other nations had one, supported with taxes. While hammering out the Constitution, they had an idea of the First Amendment, but were trying to square that with a national religion. Since pretty much all nations had sponsored religions, one of the Founding Fathers said "let's just support them all". Jefferson (IIRC) said "no, we don't support any". Obviously, that latter position won the day, and the government is not allowed to support the establishment of any religion.

Some states already had official religions in their state constitutions, and I'm not sure how that was received. But it ultimately was ratified, and those provisions of the state constitutions were nullified.

Where are the Satanists? Usually, when some bat-shittery is going on, they file a suit for equal access.