Talk to her about your own beliefs as well. When disagreements arise, reassure her with statements like: "even though we don't believe the same things, I support and care about you, and want to know more about what you think." Knowing that you're receptive to her views will make her much more comfortable sharing them with you.
Reinforce her willingness to be open with you. Just remember that everyone has their own convictions that play a part in what they're like-these are hers. Discussing religious beliefs with new acquaintances can be awkward. Make her comfortable by letting her know she has nothing to hide or feel self-conscious about.