How do I tell my girlfriend I don't want to have sex anymore until marriage?

I've been dating this girl for about 8 months now. We have been sexually active basically throughout this entire relationship. For a long time I fell off with my faith. It is something that I feel I very much need to get back into, in fact I recently spent a good amount of time by myself praying to become a better Christian again. I love my girlfriend very much and I want to tell her that I think we should stop having sex and wait until we get married. I know this is the girl I want to be with for the rest of my life. She makes me a better person in so many different ways. But I'm afraid to tell her that I don't want to have sex anymore. I don't want her to think it's because I don't find her attractive, I just know that in the eyes of The Lord, sex before marriage is a sin. How do I tell her that I just want to love her unconditionally and be with her forever, but to wait to have sex again until we're married?