This is not a reasonable complaint unless there is no discrimination. If there is discrimination then it’s entirely reasonable to target it.

I mean there are plenty of caste based systems in many religions, perhaps of relevance to the US are Mormonism and Scientology which both have ranking systems that determine options for people in the religion (and who have tried to leave it).

It's also worth noting that if you are born in a specific caste, and convert from your religion, you will still be subjected to caste discrimination from the folk in the original religion.

Obviously under the rules of the current Supreme Court anyone can claim their bigotry is because "religion" and carry on doing it. Don't want to serve someone? claim doing so violates your religious beliefs. Renting a property? ditto. Employment? again.

I don't think Mormonism/LDS has anything like the Hindu caste system (I neither know nor care about Scientology)

I'd be interested to know whether any other major religion has anything quite like the caste system.

Mormonism and scientology both have castes, albeit in varying forms of "ranking". A person of a lower rank is always subservient to the higher ranked version, which is castes.

There may be a degree of mobility between ranks, but mormonism at least makes it explicit that a black person for instance starts at a subservient rank, and can never reach the top rank, as that is reserved for white people.

Your position in a job, or the availability of that job, or housing, or in fact anything, should never be restricted simply due to some religious doctrine.

It is though. It’s exactly that, a “ranking” passed from father to child that’s relatively influid.