Your ignorance of history and reality come to mind. The excesses of those states were not due to a lack of religion, they were attempts to replace the role religion plays with another ideology, which has much in common with the more fundamentalist sorts of religion. The only reason the Christian churches are as tolerant as they are in much of the West is because they haven't the power to be anything else. When they did have the power... well, read up a bit on life in mediaeval Europe, and examine contemporary nations where religion has the power of the state behind it.
And I suppose in your usual way you'll just give me another red one for that rather than trying to form a cogent argument against it.