I've been in your shoes twice flippin and one ended up in divorce and the other we are both out and enjoying life.
The first, love was lost between us. In fact, I never had the courage to tell her how I felt about the "truth". We seperated for other reasons but if I had told her then she would have blamed the divorce on that and not on the issues between US.
With my wife (current), I was confident that she loved me and that we could work through my feeling about the religion. Mind you I was a little scared but I loved her and felt it was fair for both of us that she knew. I told her exactly what I felt and that I would not be there in heart or mind but I would physically accompany her when I felt like it. I also promised that I would not stop her from going. At first there were some minor arguments but I tried my hardest to not overwhelm her. I would attend every now and then and she would not give me a hard time when I wouldnt go.
Eventually she, out of her own, came to the same conclusion as me: its BS. It wasnt my love or patience that paid off, it was hers. She loved me more than any org and was patient enough to work whatever disagreement out with me.
If me telling her would have ended this marriage then would it have lasted if some other big disagreement or problem came our way?
Ive learned many things being married twice at such a young age, sometimes two people just shouldnt have gotten married. NO one gets married and thinks "well we are ending up divorced one day". Time eventually proves if you are compatible and if your love can endure all the problems that lay ahead.