Most Helpful Girl
Communication is key. I think it is vital that you tell her why you are breaking it off with her. You can't leave her hanging. Maybe she would realize something about herself that she needs to better, or maybe that you need to better. Depending on the situation (sorry not a lot of details were provided).
I would be so angry without a reason. I would be even more angry if I was lied to. Some guy told me he needed to fix his relationship with God. I'm not stupid I know something was up. Just please please please please PLEASE tell her.