I think you are wrong. Extremism certainly has caused a lot of bad stuff, but the Christians I meet have been, without exception, very cordial and pleasant folk who only are sad when they learn of my own atheism. Christianity gives people a life structure that benefit many and certainly regular churchgoers live, on average, happier and even longer lives than others like me who don't even engage in dangerous behaviour. It's difficult to explain. I agree with you over some of the extremists you name, but they are not Christianity, which has seen the worst days of its own extremism in centuries past and is now reformed. Now the threat is Islam, which is still red in tooth and claw. Extreme ideology of any kind breeds fanatics, beware of it.