> People need to be careful about believing anything taught by an organization when that organization's very survival depends on you believing that thing.
I think you're off the mark here. Your brother-in-law doesn't believe what the church teaches. He believes in the effect he sees it having on his own life (and maybe also the effect that not having it has on his own life).
Yes. And he has been told every day of his entire life, by said church, that he can only get that effect through them. High demand religions are an entirely different beast. They control every aspect of your life.