I take it you're not DF'd or DA'd, just faded, ... 30 years = an extremely long fade.
Why does this irk you so? You need to get to that.
Suggestion: Say, "Thanks mom!" and ignore it.
Invite her to lunch or dinner and talk about other things. Every time she brings up "all things JW," simply say, "That's nice," and change the subject.
Take control of the frame and stop letting your mum's religion get to you.
It only controls you if you let it.