The thing is, even if we didn’t declare war on Germany, Hitler would have (and actually did) declare war on the US, precisely because Hitler believed the US was run by Jews.
Why would Hitler go through all of the trouble of killing Europe’s Jews, and leave the country that in his mind, was still run by Jews, alone?
To Hitler and the Nazis, the war was all about eliminating the Jews, and as a byproduct, gaining ‘lebensraum’ for the German people. That’s why the Nazis were willing to sacrifice resources, that normally would have gone to the military, for instituting the “Final Solution.”
It was easy for the Reich to demean, isolate, mark, and then whip the populace into a frenzy against the Jews. Those who were prosperous were high profile, and the recent economic ills the Germans had suffered were relatively easy to blame on the Jews.
The presence of such a ready scapegoat was further engineered to be used as a unifying factor for the remainder of the population (one of the dangers of mob rule).
It is highly likely that Alinsky studied the dangerous mob anger (groupthink) phenomenon exhibited by many of the German people during the years leading up to the war.
The same sort of anger can be capitalized upon in the US (pick a target group), especially with the current echo-chamber mentality applied in the MSM and in politics.
That is incredibly dangerous to a society and government which has as its basis the protection of the rights of the few against the many, even if we may find the few (ecowhackos, troofers, OWS, whoever) to be people we disagree with or don't like.
When we 'criminalize' believing differently, we set the stage for slaughter in our own back yard.