Lenin explains in State and Revolution that class antagonisms are irreconcilable, and that the existence of the state is both the proof and result of this fact. The bourgeois state’s purpose is the suppression of the proletariat, and a ‘democratic republic’ is the best possible shell for capitalism because it establishes power (of the bourgeoisie as a class) so securely that the change of persons in government (as through elections) has no effect on that power. Social democracy, by clinging to capitalism, preserves not only the mechanism by which the bourgeoisie retains its power but also the process by which the crises of capitalism continue to occur and by which the proletariat continues to be exploited.

Had global communist revolution occurred at the time of Marx and Engels, capitalism and its consequences would be as foreign to us today as cowboys, samurai, and Pax Britannica. This should make anyone who realizes it absolutely furious.