It is difficult for us to understand, but parts of the Islamic world are split between Sunni and Shia Muslims. They don't mix, and they don't like each other.
In the former Yugoslavia, you have Muslims thrown in with the Orthodox and the Catholics -- three of the great world religions trying to live in the same region.
It worked as long as all three had Tito to hate. But when communism fell, they set to fighting, Yugoslavia fell apart and we're still over there keeping the peace.
During those years of warfare, I recall hearing sad stories of neighbors of different religions in small towns in Bosnia who once were friends but who ended up shooting each other, or touching stories of those who were expected to shoot each other but remained friends.
In the small towns around here, you have to search hard to find an equivalent source of strife.
The Catholics and the Lutherans have pretty much buried the hatchet. Although the clergy know what separates them, the people in the pews don't give a flying rip.
Intermarriage is no longer an issue. A coin flip at the 50-yard line usually settles the matter of which religion the offspring will be. I mean, they'll probably switch later anyway, or turn Buddhist in college.
No, the biggest division in the small town in my lifetime happened in ninth grade, when they shipped half the guys in the class down to the Ag and Auto Mechanics wing and the other half into Band, Choir and Algebra.
That division created a schism which has lingered through the decades.
After ninth grade, the willy-nilly innocent friendships of childhood ended. An iron curtain of class distinction descended. The Ag and Auto Mech guys viewed the Algebra guys as effeminate wimps, and we Algebra people viewed the Ag and Auto Mech guys as a little dim.
Friendships between the factions happened, but were limited to the football field or the school bus. In the hallways, you didn't speak to the other side.
Most of my childhood friends ended up being Auto Mechanics guys. After the schism, I pretty much started from scratch, scrambling to find new friends in Algebra and Band.
Every now and then, you'd catch the eye of one of your old buddies across the battle lines and there'd be a tinge of recognition and regret, but it passed. We knew where we belonged.
As the years have gone by, some of the distinctions have blurred.
For instance, one of my Algebra friends scored a real coup and married a beautiful girl from an Auto Mech family. Things have gone surprisingly well.
But for the most part, the division between the two cultures stuck. You can tell because when you talk to somebody from the other side as an adult, even if it is just to buy an air filter, there's a sense of relief when violence doesn't break out.
Sometimes, there are touching exceptions.
Early on a Sunday morning just before Memorial Day while ago, I was out in the cemetery planting flowers on somebody's grave. I had the cemetery to myself. It was perfectly still.
Then I heard a roar. It was an Auto Mech guy in his souped up Chevy. He pulled into the drive. At a low rumble, he made a pass through the graveyard.
Out of the corner of my eye, I saw that when he got to the grave of a relative, he tapped on the brakes as a sign of respect. He did not stop. He did not look at the grave.
As he rumbled back towards the highway, there came the uncomfortable moment when we both knew each other knew that the other one was there. It could no longer be denied.
What to do -- wave?
Nope. As a sign of mutual respect, we ignored each other. He was embarrassed enough to be caught in the cemetery by an Algebra wimp, and I wasn't about to grovel for the approval of an Auto Mech bully by waving like a fool.
As he pulled onto the highway, he squealed his tires and rapped his pipes as if to shed any lingering traces of sentiment and tenderness.
And I continued to plant petunias.
It was a touching moment of cross-cultural understanding.