IF she had not asked me 'who I was fooling." the only reason she had for asking such a question is if she believed I WAS 'trying to fool' (that is, lying to) someone. If I'm lying, then I believe something different from what I am claiming to believe...and she then went on to tell me what she thought I was lying about.
I do know the difference between 'your church teaches' and 'you believe,' even if it IS a bit mind boggling for someone to actually think that a woman who has been studying her own religion for half a century wouldn't know what her church teaches. However, when I am accused of 'fooling people,' i.e, lying about it, then it becomes personal. Then she is telling me what she thinks I REALLY believe....and what I"m lying about.