Lately, I've been reading the history of Jihad. The Muslims have been at this violence against heathens (that's us) for the last 1300+ years. Non-stop violence of the most imaginative cruelty they can muster.
The most stunning thing to me is that I've read and enjoyed history for some 50 years, including a couple of years of it in college, and I never had a clue that this pox has existed on humanity since the 600's. Only their infighting and primitive technology has kept them from conquering the world.
It is as if we have a cancer on humanity, and our immune system has been tricked into letting the cancerous cells pass without harm.
(Don't tell anyone that it was the destruction brought about by the Fatimids that gave rise to the force behind the Crusades, either.)