Disapproval of religious interest isn't really a disapproval of an interest. I doubt there is much disapproval of scientific investigation of the evo-psych reasons for religious belief.

Interest in religion is just a fancy way of saying flirtation with the beliefs/worldview offered by religious faiths. Thus the derision is no different than the average person's derision of people who take seriously the idea that the world might be flat or that dogs can talk. The difference is simply that religion is thrust into your face and life substantially more frequently than most people encounter nutjobs insisting the world might be flat (in a topological sense no telportation in weird coordinates).

Well and a generous sprinkle of the superiority complex all persecuted/socially rejected groups develop to salvage their pride. I mean psychologically it's very difficult to resist the easy option of going along with the flow without some form of personal satisfaction (I'm smarter than them) derived from maintaining that difference.