Marxists and Neonazis are in total denial about the fact that Marx was racist and antisemitic:
Marxists pretend to be "inclusive" and "anti-racist", so the fact that their entire ideology is based on a horrible racist and antisemite gives the massive cognitive dissonance, although their ideology does include those aspects of Marx's personality
Nazis live in the delusion that National Socialism is somehow different from Marxism, although Hitler himself used to be a member of the KPD, the German Communist Party, and kept repeating that he really was a socialist