The question is, does the owner of a private business that accepts no Federal or State funding have the right to refuse to do business with or associate with people they don't want to? For ANY reason?
In Oregon (I think) they successfully prosecuted the bakery that did not wish to provide a cake for the wedding of a gay couple. Last I heard, they were in danger of shutting down or had shut down due to the legal fees and penalties, which were something like $150,000 - the punitive damages, not counting legal fees.
Let's say you open a store for kids - candy, teddy bears, Legos, etc. It's expressly oriented toward children and their parents. The president of the local chapter of NAMBLA decides to start patronizing your store. Do you have the right to refuse to serve him in your private establishment? SHOULD you have the right?
What if you operate a private flight school, training amateur pilots? Should you be forced to train Muslims if you don't want to?
How about if you offer private lessons in locksmithing? Should you be required to train someone who is a known and convicted rapist?
What if a post-op newly-female patient wants to come to an OB/GYN for a PAP smear - formerly male, now surgically modified to appear female? - hint, this HAS happened, and I know the physician who saw this patient... because they "wanted the full female experience"... including annual pelvic exams and PAP smears. <smh>
All completely different scenarios. pedophiles are not protected by law. Bottom line, you can't discriminate against someone on the basis of religion.