While I totally agree with you, consider this. do you really want to spend the rest of your life with someone who was so stupid and bl<x>inkered in her view of life that she would allow a religion to dominate her thoughts to that extent? From the outside it sounds like you dodged a bullet.
She IS happy, for better or worse. I am an atheist, but I would never deny anyone the comfort of their faith. Let her be. She has made her choice..
Get a new GF.