...My gut tells me she should be allowed to attend church because it's the right thing to do. My mind says that she should be allowed to attend church because it's her right. And even if she wasn't religious, well... that doesn't mean this would not have happened.
It goes without saying, though, that there should be strict supervision of her activities. If nothing else, because she's a threat to herself. And it's not too far-fetched to say that those who are threats to themselves are threats to others as well.
All else fails, bring the church to her instead of bringing her to the church.