Hi, Ebby. Welcome to the forum!
With this being a supervisor it is especially important to set a clear, respectful boundary with her. Buhdee had a great response, but since this is a supervisor, maybe just tweek it a bit into the form of a question.
Maybe, "I'd love to have lunch with you. I'm wondering though if this has anything to do with discussing religion or the Bible? You should know that I make a point of never, under any circumstances, discussing religious beliefs with people that I work with."
If that is what this is about, she may drop it. If she doesn't, and if she really likes you she may push it in an effort to 'save' you, you can simply say, "I understand that you are trying to help me. However, it is just inappropriate to our working relationship that we discuss religion." Then let it drop.
If her attitude toward you cools, and it may, she should come back around eventually.
At any rate, that's my two cents...
J