Have you thought about giving her something with strong rationalist themes instead? HPMoR is what I'm thinking of specifically, but other stuff could work.
If she doesn't learn how to think rationally, an atheist book may or may not work regardless. If she does know how to think rationally, it's a matter of time before she sees the inconsistencies in religion anyhow. Plus, fiction is a much more compelling read than argument books and you get to keep plausible deniability without offending her aunt.
If she does know how to think rationally, it's a matter of time before she sees the inconsistencies in religion anyhow.
Note that this presumes her to be approaching religion from a fact-based perspective: e.g. treating it as just a set of empirical beliefs. This is true for some people, but not for all. There are many people who approach religion from an emotion-based perspective, where they start from the emotion of faith which never goes away, even if they intellectually acknowledge that they have no real justification for it. And then there are peopl...
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