Ever since the Crusades, when Christians from western Europe were fighting holy wars against Muslims in the near east, western people have often perceived Islam as a violent and intolerant faith - even though when this prejudice took root Islam had a better record of tolerance than Christianity.
Karen ArmstrongThe awful atrocities of religion happened when people assume that God shares your likes and dislikes. The Crusaders when into battle to kill Muslims and Jews and cried, "God will's it." That was their battle cry. Obviously God willed no such thing. The Crusaders were simply projecting onto a deity they'd created on their own image and likeness, all their hatred and loathing of these faiths and made it endorse some of their most awful prejudices and lethal prejudices.
Karen ArmstrongIf your understanding of the divine made you kinder, more empathetic, and impelled you to express sympathy in concrete acts of loving-kindness, this was good theology. But if your notion of God made you unkind, belligerent, cruel, of self-righteous, or if it led you to kill in God's name, it was bad theology.
Karen Armstrong