Well, to tell the truth, Heinrich Himmler was rather fond of Muslims, and felt that unlike limp-wristed Christians, Muslims were predisposed to being superb warriors.  Thousands of Muslims did in fact fight for Nazi Germany in World War II, both in Wehrmacht units and also as members of the 13th Waffen Mountain Division of the SS HandscharWaffen-SS.  The latter, especially, did earn a reputation for brutality and ruthlessness.  And to this day, you do not want to venture into parts of modern Serbia with the checkerboard insignia of the Croat Legion on your sleeve.  Doing so is an invitation to having your throat slit, especially after dark.