Even as the Fascist leader, Mussolini never concealed his sympathy and admiration for Communism: he thought… — Richard Pipes

Marxism and Bolshevism, its offspring, were products of an era in European intellectual life that was obsessed with violence. No-one embraced this philosophy more enthusiastically than the Bolsheviks: ‘merciless’ violence, violence that strove for the destruction of every actual and potential opponent, was… the only way of dealing with problems.

Bolshevism and Fascism were heresies of socialism.

The French Jacobins were the first to realize the political potential of class resentment. Exploiting it, they conjured constant conspiracies by aristocrats and other enemies of the revolution: shortly before their fall they drafted legislation expropriating private wealth and had the unmistakable communistic implications. It was from the study of the French Revolution that its aftermath that Marx formulated the theory of class struggle as the dominant feature of history. In his theory, social antagonism was for the first time accorded moral legitimacy: hate, which Judaism condemned as self-destructive, and Christianity (in the guise of anger) treated as one of the cardinal sins, was made into a virtue.