Morality As a Limit
Multiculturalism is a belief derived from Moral Relativism. It claims that since all ethical systems are equally good or bad, we cannot judge people outside of their own ethical beliefs. It holds that a tribe of blood-thirsty cannibals is not morally worse than a civilized, peaceful nation. It holds that Nazi Germany was the equivalent of the United States.
Mutliculturalism accepts slavery and freedom as equals. It accepts murder and theft as the equivalent of peace and prosperity. If a country is starving due to its policy of government intervention in the economy, multiculturalism doesn't care. It assumes the people under the system must have picked it, and therefore they are happy with it. Since value is subjective, no country is better than any other.
Multiculturalism manifests itself as anger at those willing to compare cultures. It claims that any culture is as good as another, as long as the culture does not claim its superiority. Any culture that believes in absolutes and is willing to measure itself to the rest of the world is evil.