My girlfriend stopped having sex with me

Me and my girlfrind are going on 3 years now. We both have tertiary educations and have always enjoyed logical and rational discussions. Neither of us were very religious, i.e. we didn't go to church but both of us grew up in christian homes. A few months ago she was diagnosed with cancer, which thankfully is now under control. Our lives were a pretty decent mess during this time, and we both were under considerable stress.
Before all this happened we had a very healthy sex life, but a a month or so after she was diagnosed she started getting very religous and joined a church. Soon after this she told me that she does not want to have sex any more because its wrong in the eyes of God.
For me the sexual intimacy we shared was a pillar of our relationship, and I felt that it was wrong of her to force me into a situation where I have no say on what happens to this pillar. I thought that the underlying reason was that she felt less sexually appealling because of the sickness and that it would change with time. Anyway I went along with it but she knows it bothers me.
Our lives have now returned to normal, but the sex is still abscent and she intends to keep it that way for religious reasons. Im fairly sure she believes that she got cancer because God was punishing her. I feel very strongly about her, and I would like to spend my life with her. But this is building a gap between us, and we are getting less and less intimate. I dont know how we'll survive this if it doesnt change. I have respect for her beliefs and dont want to hurt her, but it doesn't seem like she is taking my feelings into account. It feels to me like I am in compitition with God, a battle which I won't win.
I she right to do this? It feels like she abusing my respect for her. I have been wondering about God alot lately myself, and a question that keeps coming to mind is how is it right that her getting closer to God is taking me further away from Him? I dont know the answer to this, and I don't know what to do about the gap between us. Please help.

ps. It's worth mentioning that she simultaneously admits that there is a gap between us and that "she loves me more than ever now" (an obvious contradiction). That latter I have learned is part of all the "reasons to abstain" guidelines on christian websites.