Most people -- including the ones who are proud of being "independent thinkers" -- get their opinions and behaviors from the people around them that they identify with. "People like us" believe in X. Be a non-conformist: dress like us! Around here, that's "not done." Partly, this is because you just can't investigate everything yourself, so checking your opinions against those of others you identify with is a shorthand way of coming to a reasonable conclusion. And partly, of course, we do this because all of us want to fit in somewhere, to be accepted and loved -- and we are equally afraid of being cast out for being different.
Peer pressure doesn't have to be a negative, though it often is. Where the Church maintains a strong culture, it exerts a positive peer pressure on those within its orbit. We imitate those we admire as a means of imitating Christ, as St. Paul recommended. Then, as we say, Christianity is "caught," not "taught." But where the Church's culture is weak, where the styles and buzzwords and values of the surrounding society are seen as more attractive, then the Church becomes more like everybody else. In those cases, the Church can be a haven for dysfunctional behaviors of all sorts.