I understand the cross, because I'm a Christian. But you can bet your sweet buns that if someone was to display a pentagram...that the rules of that office would change.
In my office this was the case. We had a witch and a warlock (they openly practiced wiccan and witch craft) wore their pentagram jewelry and some Christian clients and the office staff complained. (Which I think was very unfair...I really believe you have a constitutional right to worship how you chose) So there was a policy that not displays of religion could be worn or displayed in the office period.
But the to answer your questions. I was raised a JW and left become Agnostic and now I consider myself a Christian. So I believe you should be comfortable to express yourself and display your belief if you chose. Everyone should try to learn to be more tolerant of different views. But I know most ....especially Christians are not.