Consequences of different beliefs - Telling a lie about telling the truth & vice versa.

It's said that "beliefs have consequences" and I find it interesting to think about what different consequences different beliefs have - e.g. what are the practical consequences of "adopting" the Muslim, Christian (Catholic versus Protestant, Evangelical) etc., Jewish belief "sets". This sort of relates to quantum ideas, I guess - what difference does the actual relationship of the "belief sets" to "external reality" (to the extent that such a thing exists - if a tree falls in the forest etc.) have on the holder of that particular "belief set". Is it better to have some "belief set" rather than none - even if that "belief set" is not exactly congruent with reality? Do we have to lie to ourselves about the truth to make it bearable ("You can't handle the truth!")?