On a balance scale, they are on opposite ends and are each others natural enemies. Extremist Republicans and extremist Democrats love each other in comparison.

Nazis are pure evil, have Nazism excluding view of the world. "-We, are good and righteous and they are inferior and should be our slaves". Socialism has the opposite view, "we" for a socialist is really everybody, it's an inclusive view of the world. a true socialist are tolerant, a Nazi are not. I have strong socialistic feelings, are very tolerant but HATE Nazis because of their lack of tolerance. Actually, a good Christian and a good socialist have a very similar view of people, up to the point that I have often heard the the phrase "Jesus was the first socialist", not really true but the idea of helping and caring for each other exist for both the Christan and the socialist. There are also many religious socialists.

Don't misstate socialism for communism, Socialism are included in correctly built communism but can also exist in other systems like Social democracy that was inspired by the communistic idea but better suited for the reality.

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Whoever fights monsters should see to it that in the process he doesn't become a monster.
Friedrich Nietzsche