:’) The main reason for the left’s opposition to Hitler was, he attacked Stalin’s USSR. During the period between Hitler’s rise from obscurity to the phony war period, the Commies saw Hitler as the best possible leader for Germany, even as he purged their fellow Commies inside Germany. The Molotov-Ribbentrop non-aggression pact dropped a bomb on everyone at the time (at least those interested in politics), as it appeared that Hitler and Stalin were allies (which in fact, they were for a brief time; at first, Stalin reportedly couldn’t believe that Hitler attacked him, and Stalin wasn’t a sentimental guy).
You have a gift for understatement! :-))