Perfection-
I was thinking what Outlaw said. I wouldn't try to push the religious issue. If you want to have a relationship with her, you might just need to let that be something you ignore-sort of like the proverbial elephant in the middle of the room. My Mom still tries to preach to me sometimes. I just respectfully stay quiet and try to let it roll off my back. I don't try to convert her because I know that: 1. It's a lost cause and 2. she would be lost without the social structure she has been building-exclusively within this religion-for 30+ years.
Sadly, I do find that we naturally don't spend lots of time together partly because of the preaching-and partly because she can't come to any of the family gatherings I have-kids' birthdays, soup supper on Christmas Day, etc. ad infinitum.
I don't have any wise words for you, but I can tell you that I can honestly say I know how you feel
(((((((Perfection)))))))
Jewel