The Roman Empire was fizzling out by the time Christianity was installed, and was splitting apart by the time Mohammed was born. The Muslim sweep through Africa and Asia Minor was savage (as they remain still), and the Crusades to return access to Jerusalem was savage but not according to accepted combat at the time
. Columbus didn't have to massacre the natives because the old world diseases they unknowingly brought with him took care of that. The slavery and abuse of the new world was not brutal at all anywhere in the world at that time. You are judging people from 800 years ago by our perspective, in a mostly peaceful world made that way by Christianity.
However the brutality of the Muslim followers has not changed in the last 800 years.
I'll give him being a great wartime president, not trying to run the show as Hitler did. His economic stupidity prolonged the depression here longer than virtually anywhere else in the world. The stock market didn't return to pre-war levels until the late 1940s
