I think part of that (specifically Catholic) stems from the fact that it's one of the few religions that is compatible with a scientific understanding of the world, where science is seen as a worthwhile study of creation, and not something that's dangerous and evil (like many modern fundamentalist groups seem to think).

The danger IMO comes when people tie their religious belief too strongly to political movements, or think that just because there is doctrine around a certain aspect of human culture/life, there is no questioning it or investigating it further. A healthy skepticism (especially over one's own beliefs) is central to a good life IMO.