Seriously.
BYM does not indicate that she is no longer believes in the religion. On the contrary, she writes:
“If I didn’t have some belief (I like to think of it more as konwledge) I wouldn’t be interested in learning gemara. Or anything Jewish at all.”
You are scared that someone is not as confident as you are about everything you’ve so willingly accepted without question. It is not her lack of belief that is bothering you. It is your own insecurity. You just don’t like people whose thoughts undermine the system you are so comfortable with.
Well get used to it.