You should do and say whatever you feel is appropriate. That may not sound very helpful, but no specific answer will be appropriate in all situations anyway.
I suppose you might want to consider whether you want to get into it and weigh things out and see if it's worth it given the amount of time you have left living with her. Of course, I don't recommend going super apostate on her all of the sudden, that will only make her defensive. You might just hold that awareness though and make it a point to question something that really sticks out as a sore thumb when the opportunity arises. Just leave it at an open question, and treat other things with the same open attitude, this way there's a better chance that she will be open to really consider the question when you bring it up. You might be tempted to draw the conclusion for her, but unlike the typical "bible study" where the "teacher" might eventually spell out the right answer for them, if you leave it open there's a better chance that something might actually change. Basically you're going only as far as she's willing to go, supporting her opening up rather than tearing her a new one, to draw a sharp contrast. You know, you might approach it kind of like service and make return visits on her, just don't let her see your notes if you should decide to take some.