I've said in other posts that FI and I are both Atheists. We aren't militant, we just don't believe. We respect that others do, and would never think of trying to push our own beliefs on family and friends. This has mostly worked out okay for us, except in a few circumstances of family members just not getting it, but for the most part it is okay, because we just try to not talk about it with others.
However, FI's paternal grandmother married a minister after her husband died of cancer ten years ago, and has since become a born-again Christian. We received tons of paraphernalia from her in the mail... pamphlets and booklets telling us we were going to burn in hell for all of eternity. FI called her at least 10 times to ask her to please stop, and the mail increased. She also put his cellphone number on calling lists for a bunch of religious organizations in hopes of "saving" him. After giving her one more warning to no avail, FI sent his grandmother a satanic bible. This was an extremely poor decision on his part IMO, since rather than making her understand that we don't have any beliefs about anything at all, this move made her believe that we are Satanists, which couldn't be further from the truth. However, it got her to stop. She hasn't seen FI or spoken to him in over two years now because of this.
Now she is in town for Christmas, and has requested of her son (FFIL) that we invite her and her new husband over to our home for dessert tonight. FI resisted, but FFIL talked him into it somehow. We just had one condition... they are not allowed to bring any religious material into our home, and they are not allowed to speak about religion to us during their visit or they will be asked to leave. Oy vey! Now I have this lady, who I have never met, coming to my home tonight against both of our will. I'm just hoping that she's coming to make amends and not to cause more drama, although I doubt it (she gave FSIL who is also an Atheist a book entitled "God created all" for Christmas with the idea of getting a rise out of her). I think the last thing we need from that side of the family is more drama.
Wish me luck!
ETA: I don't want anyone religious to take this the wrong way. As I said, your beliefs are your beliefs, and I feel strongly that everyone is entitled to their own belief system (or lack thereof). I'm just venting about her inability to act the same way towards us.