1.) She's the only one in her family that is super-religious. 2.) IMHO, there has to be something that made her this way. Am I being paranoid, or is she probably a fucking lunatic?
Well, I don't think a post can do much, but all I can say, for the moment, is that there's something I noticed in my 24 years of life in this world, and I will never stop learning lessons by Mrs. Life, but so far I learnt that people are many, people can be good and bad, people can be friends or enemies, and people are so different, about religion too... considering the people I've been dealing with, I've come to think that usually, people who need a lot of reassurance and are quite weak at a certain point of their life, if before they were just normal religious people, then some of them happen to find like a sort of a shelter in religion , expecially Christianims, because in it it's all so "already-written", it talks of a "happy-ending" if you follow its let's say rules and way of thinking, and it seems to give you the reassurance you need, says that the poor ones and hurt ones will surely get justice by the "hand of God" someday, and promise you the happiness forever, and many more things.
I think that believing in God or not believing in any, it's a personal choice and should be respected in both cases. Freedom about thoughts exists for a reason.
But when religion becomes fanatism or excessive dedition to it -although, in theory, what is an excess for others, is not usually considered as an excess for the person who is involved first of everyone else- that make you stay closed in the "box" of your own world only, then I personally think it's bad and not productive, for your life. I think one can choose to be be religious, without any exaggeration though.
Now, I don't know this girl personally, so that prevents me fromg giving any good advice and doesn't allow me to understand the matter all round, since seeing her with my real eyes and having conversations with her would help much more to understand her world and the reality that surrounds her, the way she sees things, perceives them and reacts.
But all that I said, was basically to mean that I don't think you're paranoid if you thought that something happened to her, Dred.
Although it might sound paradoxal, I believe there's not a reason for everything that happen, but concerning this girl, I think that maybe there are good chances that something important, and that affected her a lot, happened, to the point of making her become the way you say, different to the rest of her family and so on, and the reason why I think this is what I said before. Obviously, it's only my opinion, no certainty in it.
My only advice can be that if you are really interested in her, maybe you could try and talk a lot, about anything... yourself, herself, life, hobbies, music, things and passions you might share, anything, even the religion that she considers so important to her, so she can feel good with you and not "different" or "judged" (because sometimes people like her are made fun of by other people who hate religion and so on) and make her understand that you are disponible to dialogue, not in an aggressive way though, because people like that usually get scared if they meet someone who act too impulsive and ain't disponible to speak their mind in a "genuine" way, without any hurry because maybe it might take a long to get to know her inner world and thoughts.
My opinions aside, hope you'll get to sort out all your doubts and make good decisions.
Anything you will do, and anything that might happen, good luck, Dred.
(ps: sorry for writing a lot, and for any possible mistake.)