Walls
There’s an old joke about a man who is being shown around heaven for the first time, by St. Peter, who walks around pointing out the various glories where people of all colors and ethnic persuasions live — grassy hills, green meadows, still waters, symphony halls, silent spaces, steep hillsides for people who want to hike to the mountaintops or the ponds, and so on. Then they come upon a great walled fortress.
“What on earth is that?” asks the man. “Oh,” says St. Peter. “That’s where the fundamentalists live. It’s not heaven for them if they think anyone else got in.”