If the question is "Should I, as an outside observer, do my best to convince Wednesday religion is wrong?" the answer depends on your moral system. I'm a utilitarian, so I would say no - I think it's a background assumption here that she's happier being deceived.

( I hope it's ok to respond to such an old comment...)

Um, but IMO most humans will be happier if they become atheists ( eventually). AND, what is far more important, with every new atheist the Sanity Waterline will raise which in turn increases the likelihood of surviving existential risks. And that should be ( or at least close to) the primary concern of every utilitarian. There are many more reasons I can think of, but these should suffice;) Or do I miss something?