Should she bring up religion, I am to remind her of her prior HR meeting regarding the subject and tell her she is violating the restrictions placed upon her during that meeting (his guess is that they placed restrictions on her).
This is great news. Don't be afraid to do this. My guess is that you don't like confrontation, because you didn't tell her to STEP the #*$& OFF when she interrupted your conversation with your client.
Don't allow her to make your workplace miserable. The very fact that HR has to step in your behalf raises *you* on the radar screen too!
Lisa