Again, the wars were started by Islam, and it was Islam that treated Christians and jews as 2nd class citizens -Dhimmi- . You should read Ba'at Yeor's books on the subject, it was really pretty nasty. A status about like free blacks in the old south: no say in things, no rights, can't testify in court, can't defend yourself against a moslem, ad nauseaum.
I'm not suggesting the Christians didn't get carried away, but, rather that once the Moslems started their intended conquest of the world for the old Arabian moon god, they really can't complain about the way people fight back.