A lack of shared philosophy means there's no open, shared spaces. Like tonight, I'm going to a Knights of Columbus meeting. On Thursday, we're leading marriage prep at our church. On Monday, it's my men's club meeting. Later in the month, we're having a church BBQ. Most of the time, we're over socialized.

For the elderly, we have a shut-ins ministry to visit them. For the poor, the Vincent de Paul society still goes two-by-two to all those who have asked. We've gotten rid of churches, replaced them with nothing particularly inspiring, and now we're wondering where all the social cohesion went.

EDIT: I will point out that I'm not restricting myself only to churches here. I think, in the past, America also had this characteristic -- anyone who believed in American ideals and sought to further them was an American. De Tocqueville mentioned this quality of Americans (every American is a president) in his various writings on American social structure. Unfortunately with the rise of identity politics and ethnic factionalism, we've lost this notion of 'America as an idea', as is seen in the reluctance of people to serve on juries, for example.