Hi hooah212002
just one thing to remember is that people are often emotionally attached to religion because it may be a part of their family culture, or they may believe that God is really there and this is an emotionally comforting belief.
so when you try to reason with her, just keep in mind that she may be emotionally attached to the idea of a creator. My guess is thats why your discussions become heated.
I cant advise you on what to do but I can tell you that you can still have a good strong relationship with her. My husband and I both have different beliefs and we also used to get into heated arguments over them. But we've come to a compromise now and its working very well. We dont challenge each other the way we once did. When we did challenge each others beleifs, thats when we became at odds with each other.
So for us the key was to not challenge each others beliefs. We accept that we both think differently and we put it in a box and leave it there.
good luck.