Ever since I was a kid, I've heard a great deal about Ashura and the tenth of Muharram. Most of it is unbelievable and I suppose kids on both sides are told such things so they will not convert and go over to the other side. 

The most prevalent beliefs are that the world was created on the tenth of Muharram and that it will also end on the same date. The first of course is incredible, because the day the earth was created should have been the first of any month. About the second, the less said the better. The world will end on a Friday (and it will be tenth of the month). For many years after I heard it, I used to scan the calendar and see if the tenth of Muharram was falling on a Friday. If it was, I'd be convinced the world would end on that day. 

In 1979, I went to a Shia officer in a position of power. He deliberately did something that caused me to spend many sleepless nights, as it would have meant a huge financial loss to me. I learned later that most Shias have been told that they should cause as much physical harm and financial loss to Sunnis in the month of Muharram (so they can easily enter heaven). Strangely enough, in 1986 a Shia inspector said bitterly to me, "You Sunnis try to harm us as much as possible in the month of Muharram". 

Then there are certain names that are anathema to the Shias. A neighbor of mine named Farook (his father was a Shia but mother was a Sunni) wanted to marry a Shia girl. When the cleric solemnizing the marriage read the groom's name, he refused to proceed. It took a long time to convince him that the groom was a half-Shia and would be a full Shia for the rest of his life. Shias will never name their female children "Aisha", while male Shias will never have names like Abu Bakr, Umar and Usman. Contrary to this, Sunnis have no objection to naming their children Ali or Fatima or Zehra. 

I believe that this hatred on both sides is due to lack of education. The Muslims who have emigrated to the West are so busy that they don't have time to indulge in such hatred, but those who remained behind talk of nothing but religion most of the time. There they are brainwashed into believing that their sect or sub-sect is the best one and those who follow other sects or sub-sects will go to hell.Some even end up killing those who have beliefs that are different from theirs.