The Roman Catholic church conducted Inquisitions in Spain, France and Italy, against Jews, Protestants and Muslims.
A few hundred years before, Christians clashed with muslims during the Crusades.
A few hundred years later, Christians persecuted, tortured and murdered people as witches in both Europe and North America.
In some colonial territories, the Christian elements were brutal with locals, up to and including American Indians. Once the Indians entered the missions in California, they were effectively held captive, such was the "agreement" or "contract" into which they entered.
The Baptist church supported slavery in the American South, and discrimination and segregation after the Civil War.
I am NOT claiming equivalencies with current muslim violence, terrorism etc.
I am saying that critics of Christianity have plenty from which to draw, in citing bad treatment of other humans.
I think the best Christian responses would be: "Yes, we recognize that, but we stopped, and condemn all such behavior now. We call on islam to likewise stop and condemn the behavior as well."
