But you might have missed the point. The idea was not to compare which peoples have commited the worst atrocities. As Christians, we are supposed to begin with the premise that all human beings are in a state of sinfulness until regenerated, and no sin or group of people are any worse than any other. All have sinned and fallen short of the glory of God. The point was to show how many atrocities in particular were commited using the name of Christ. This should send shivers down the spines of any genuine Christian. In days of old it was the Catholic church and its infamous crusades. These days it's greedy politicians backed by an elite few from the Reconstructionist or Kingdom Now movement.
Then as now, in the eyes of the world it is all christians who think and act this way, and they never see the truth.