Nearly all religions preach peace and harmony. And loads of them are soaked in blood. And we tend to forget (or loads of people simply don't wanna know) that the blood spilled "in the name of Christianity" might well outrank the blood spilled by ISIS and similar organizations by far (some of the stuff they hold against us). Why don't we see that. Because that was longer ago, and nobody is old enough to be able to have been there when that happened.