[pourush]

People don't always research what's important to their beliefs. I'd even go so far as to say it's more common than not that a person hasn't adequately researched their beliefs, whatever they are. So she might not have even read the book she got this belief from. Also, people have very different conceptions given vague data. So your interpretation of her beliefs is absurd, as religious scripture is ambiguous. Or more accurately, it doesn't matter whether it is ambiguous or not, as people will make that decision regardless of the ambiguousness of the original text.