I don't know, you have to ignore an awful lot of history to argue that Christians are more peaceful than Moslems.
Actually, all you have to ignore is the teachings of Christ to believe that 'Christians' did those killings. Where, if we actually do what mohammed taught, we would kill, if we did what Jesus taught, we would show mercy one to another.
I wont deny that those claiming to be either have killed, what i deny is that those who were genuine Christinas actually did the killing, while I have no problem believeing that those who followed Islam killed, for Islam teaches to kill!