The 1st amendment’s protection for the right of the People to peacefully assemble includes for the purpose of business. And just as the other first amendment rights are protected both pro and con, the right to NOT assemble is equally protected. Any law which forces a business to accept any and all customers or in anyway prevents the business from refusing service to customers, is in clear violation of the first amendment.
It has nothing to do with religion.
LOL ... how did that one work for stores that didn’t “believe in” serving blacks? ... :-) ...