The SCOTUS precedent

Don't worry they don't believe in Precedent anymore. You just need to grease their wheels. I hear it's cheaper than you think.

I would start invoicing people for your time until you get a legal cease and desist. Then sue them, just because they accepted responsibility.

Make it cost them money.

You could counter with a Baha'i prayer. They are still an Abrahamic religion, and they have literally hundreds of prayers for practically every topic.

And you can't disrupt the meeting by interrupting the prayer until they kick you out, because then presumably your employer would fire you, I assume? 'Cause if not, you should definitely ruin their motherfucking christofascist bullshit.

'E pluribus unum' was pretty good, but I liked 'mind your business' too.

No, it was added during the cold war because the commies were seen as godless heathens and the religious assholes in charge seized the opportunity to push their brainwashing on us using "do the opposite of the commies" as an excuse. There was never any legitimate concern about "e pluribus unum."

It's the same story as why they reflexively oppose almost anything proposed by a Democrat today.

It hasn't reached the Supreme Court for a decision, but lower courts have basically said that it's not establing a religion because it's used in a secular and patriotic fashion. (My interpretation of my understanding of the ruling).

https://en.m.wikipedia.org/wiki/Aronow_v._United_States

You can blame 1956 Cold War era Congress (red scare) and Eisenhower.