Is she doomed to a life of ignorance?

My cousin has adopted a new believe and it is awfully superstitious (She actually thinks her sister is well behaved because she took out of her sister's bedroom a Hello Kitty doll that her sister didn't even remembered it was there). She's always been so normal studying and learning all sorts of languages and been abroad and open to new things, now she goes everywhere saying the twilight movies are okay to watch because they are about Vampires and Werewolves ("Because" they're "fiction") but The Harry Potter series are not because they practice magic ('cause they're all too real). Is she going to go even more fruit loops or is she going to at some time realise she is believing in whoee and start been like her self, rational that is. I actually think she was/is the only normal person and sanest of all of our fammilly including myself but lately I think she's been going down the wrong path. Am I right to have such preoccupations?. She now has become the youngest adult nagging at her boyfriend and acting like she nows it all and real fun is for little kids. last time I saw her she was saying to her little sister that she ought to ask her friend to make her another mix tape but with out that spoof song that goes I'm a Barbie girl in a Barbie world, wrapped in plastic it's fantastic... yeah like her (my) fat butchy sister (cousin) had been real suceptible to such obvious spoof. Among others just as harmless. Also that time we talked about things related to me being gay, crushes and stuff and she acted as she never new I was ever gay (We even had a related conversation just a few months ago (before she went 'loco' in the 'coco'), before that we hadn't talked about it in years), such a hypocrite. At some point she actually tossed at their back yard her mothers depictation of the last supper because her Evangelic cult told her religious depictations brought in evilness. Me for once I think when her boyfriend goes bananas with all her 'things' and dumps her loonny ***, she'll snap out of it, maybe... she really drank the Kool-ade and had seconds and thirds. (like, she drags Mark Augustin (her boyfiend) in to this thing where they go at 7 pm and it goes on until 1.30 am -ish and at those things she goes to shake in the ground and to kneel like there is no tomorrow and then they all start screaming gibberish, later on saying god talked through all of them at the same time (WTF?), I know this because willingly I went a few times maybe three times tops and in there this sad excuse for a man tryed to persuade me trough his hands on my head and chest with 'vives' in to knock my self down in to the floor like the others, I didn't, I recall my cousin saying something like 'Someday you will, you'll see', with this shmuck for a face like she is so way above me and everyone else (She is/was better than me in a lot of things but she had never, never been so rude, all blinded in to this zombie like state... such a shame). I do not know what to do or how should I approach her What do you think I should think of her...?, so I can help, Will she let me?.