Farm people know about barn cats. They are the cats which live in the barns around their farms. They are not exactly strays, and they are not really pets, either. The farm family gives some mild encouragement to the barn cats to stick around, and some mild toleration exists between the cats and the farm family.
The barn cats are not part of the family, though. They receive no care when they are sick or injured. They receive no protection from the foxes and coyotes that live on the fringes of the farm. They may receive some occasional scraps and friendly pets, but they pretty much need to find their own food and comfort among themselves. Moreover, the only protection they receive from the cold, rain and snow is whatever place in the big building that they manage to find. If they die, though, the farm family may give them a token burial.
The people who live around the fringes of our churches, especially the larger ones, are somewhat like barn cats. They become invisible after attending a few times, when the others get used to them. They swell the attendance statistics of the larger churches, and they become part of the pride of growth. They may come forward when there is an altar call if they realize a particular need, and they may attend some functions of the church. But they are not part of the family; they are at the edge of our lives, but they never enter our hearts.
During my time as a pastor I met with many of these people, spoke with them, and developed some kind of relationship with them. Often enough, they might attend and give some hearing to my preaching. But by and large, despite my pleadings to the members of my churches, they never became part of the family. They themselves became wary of some of the church members, just as a barn cat might become wary of a little boy that pulled his tail.
Barn cats do not always socialize completely to become docile pets. They seem to miss something of the human contact in their early days that seem to keep them from forming as strong bond with families that take them in as the cats who were part of the family from kittenhood. But for those who take them into their hearts, they are as much a part of the family as the ones who became part of the family when they were born into it.