I have been down the divorce road before.
As many here have mentioned, communication is the key. Let her talk. Then let her talk some more. And then more.
Even if you have strong disagreements on religion, you have been together and know each other.
There are so many negatives or downs when breaking up. Again, I am speaking from experience.
I don't know your feelings about using a biblical verse, but you could quote the Matthew 19:6 verse that says what God has put together, let no man tear apart.
Maybe that is not applicable in your case but keep it in your pocket if she goes too far down the religious route.
I wish you the very best, but please communicate.
Rub a Dub