Hittler only sort of hated jews and he almost loved commies. About Jews Hitler said that had they not existed they would almost surely have had to be invented. He knew that in any mass movement a Devil to blame is the most important ingredient. And Hitler was also smart enough to know that extremists right and left are very interchangeable.
To easily fine these insights I recommend one of the greatest gems of a book on mass movements, The True Believer, by Eric Hoffer.