I think C.S. Lewis was writing in the 40s about this -- that it used to be that laymen hid their unbelief from the clergy; at the time he was writing, he mentions those laymen who would be reluctant to admit their faith to their clergy.
He cites those clergy who claim to have come by their lack of belief "honestly." And he says he has no reason to doubt that; what he doubts is whether, having come by such unbelief, they can honestly continue in the service (and pay) of the church.
Perhaps because Christianity is a social institution it can take on the same type of social functions of conformity, etc. Part of that, ironically enough, can be a tacit skepticism or agnosticism with regard to the more emphatic supernatural claims, miracles, etc., among some church members. In Name only types..