How should an early 20th century American know that Nazism is a bad thing?

In the first half of the 20th century America was a pretty nationalist country and had tons of anti immigration sentiment. The USA had been a melting pot throughout its history but there was a huge backlash to all the immigrants that flooded into the USA from Southern and Eastern Europe in the late 19th and early 20th centuries. <br><br>A lot of Americans, particularly in the business community and in the Northeast, really liked the idea of Fascist Italy under Mussolini and wanted something similar for the USA as a bulwark against communism.<br><br>I would guess that had Tzarist Russia not been dissolved in 1917 the average American would have been far more antagonistic to the rise of Nazi Germany than they were. But the rise of the Soviet Union made America more sympathetic to the Axis powers. After all, you had the red scare in the 1920s and then throughout the 1930s the media basically ignored the holocaust and focused on negative portrayals of the Soviet Union.<br><br>What would change an American’s mind in the mid-30s?