In my opinion, (I believe in religion and science), a good way to help with her being a religious person, is find a connection between the two, such as the big bang theory and stuff like that. If she is open minded (along with your self) that should help a lot of things, but about the calling,telling her to call less and/or shorten the conversations, can seem a bit harsh. So why don't you just try to talk, but if the conversation is going no where, just say something like, "I'm going to go" or something, but if she ask why, do express your self, just in the nicest sounding way possible.