Best single explanation I have yet heard for the decline of congregations comes from Karen A. McClintock, a psychologist who teaches at Southern Oregon University and specializes in “shame recovery.” She believes that congregations send out messages of shame to newcomers. She gives an example of a 22 year old college student named Amanda who tried going to church once, but felt the congregation was “suspicious” of her:
Without knowing it, this congregation was sending out messages of shame. They were suspicious of Amanda because the possibility of taking a fresh look at their worship and fellowship evoked uncomfortable feelings inside them too. Perhaps their worship had become rote and boring. Amanda might come along and ask too many questions, learn of a conflict they had not resolved or an incident of sexual misconduct that they were keeping secret. Seeing her painfully reminded older members that their own children and grandchildren had long ago abandoned the institutional church. They felt shame about this and about not being able to meet Amanda’s needs by providing her with a group of peers within the congregation. And the shame passed to her and back again to them. This shame tossing is all too often the present-day congregational landscape. ["The Challenge To Change," Alban Institute weekly no. 426, 24 Sept. 2012]
Notice that this kind of shame is not tied to any one theological position; this could describe many of the Unitarian Universalist humanist congregations I have attended, as well as more orthodox Christian congregations.