Obviously, employees may not wear political tee shirts because that gives the mistaken impression the company promotes some political candidates. In a similar way, an employee should not wear a giant cross or a hijab because it gives the mistaken impression the company promotes Christianity or Islam. This is especially true in a company where there is a corporate uniform such as fast food, airline or parcel delivery.
You might argue employees never exposed to the public should be given complete freedom in dress. However, they are deliberately intimidating fellow employees with implied proselytising. If employees want the comfort of religious symbols, let them wear them discreetly under their clothing. Other employees should not have to be exposed to them.
For example, the cross is the symbol of bloody human sacrifice and a call to murder gays, similar to the swastika. I don’t think some bullying Christian should be permitted to metaphorically shove that revolting thing down my throat. We over-accommodate religious superstitions. After all, religious dress codes are just traditions/superstitions with no practical justification.~ Roedy (1948-02-04 age:70)