What are my rights if I was told I couldn't wear my chain and cross on the exterior of my shirt when I work a check in desk?

I was told by 2 managers to tuck in my cross and chain because we don't want to offend a guest by wearing of this cross. My Operations Uniforms Full Standard only states that if I work in the culinary or kitchen department, a chain may be dangerous and can contaminate food and is understandable why it wouldn't be allowed. However, I work the front desk and in MGS it states: Jewelry - associates and managers when worn, jewelry must be moderate and safe for the job function. Exception: No jewelry may be worn by culinary associates, with the exception of wedding band and/or post earrings. It doesn't state anything about offending guests with religious beliefs and such as I was told by 2 different managers. Of which 1 of these managers continued to harass me and discriminate against me on how I should tuck in my cross after the fact that a 3 manager (Operations Manager) already told this particular manager to leave me alone and he'll get the detail on it tomorrow. What law has been broken here and do I have a case? I am still employed by this company and aren't looking to leave elsewhere. Get back me as soon as you can and thank you.