You are misinformed. The KPD (Communist party of Germany) was Communist/Stalinist, who the nazis were actually fighting. KPD was the largest Communist party outside of Stalin's Russia. FDR/Churchill… "teamed up" with (Uncle Joe) Stalin to beat the crap out of those nazis, or don't you remember those history lessons?
Just in case it's not yet in-your-face, sufficiently obvious: Nazis were eradicated, and the Communists went on to dominate the world, including this Country.