I'm going to call their religious beliefs ridiculous
What about their religion is so ridiculous to you?
Because I don't like blind followers of dogmas with hidden codes of conduct.
It's none of your business on what someone believes, religion is worldwide and you need to be more polite and respectful of it. You just need to say nothing at all and get on with your day, that costs $0 and everyone will be happy. They don't harm you, and you don't harm them so leave them alone.
I have a right to my opinion.
I get that you have the right to have an opinion, but you don't have to share them all. I think that religion is one of those topics that you should just try to be respectful of. Just because you do not understand it, does not make it any less important.