It's a bit of a hot button of mine and I should fully explain.

Most people seem to think that the Constitution says "Congress shall pass no law respecting the establishment of *a* religion". The meaning being that there would be no 'official' religion as there was (and is) in Great Britain.

But that's not what it says. In the misinterpreted version, they think that "establishment" is a verb, and in "to establish". It's a noun.

A church is a religious establishment. A pub could be called an alcohol establishment. In that context, "establishment of religion" is everything from a church to religious schools. It's one of the reasons churches don't pay property taxes.

One of the original reasons for that clause were the kinds of laws that were seen in Great Britain that might have said "no Irish Catholic could be recognised as a lawyer". It says the state will not 'respect' one religion or any religious establishment over another.

This is also why challenges to things like nativity scenes are ripe for misinterpretation. SOme town bans the nativity scene and suddenly the hue and cry is either "war on religion" or "no Christmas". What that really turns out to be are wimpy town officials since the Supreme Court made it crystal clear that you CAN have religious displays on public grounds but that you cannot discriminate. It means you can have your nativity scene so long as you allow a menorah, should someone ask to put one up.