Someone who challenges an established culture (usually a profoundly ignorant teenager or misguided Leftist) by claiming that it is a figment of one's imagination, a social construction, something that is entirely defined by a specific hierarchy which they see as the embodiment of evil impeding social progress. i.e white-supremacy, patriarchy, Islamophobia, etc

This person is also incapable of saying anything positive about their identity/culture. They are thinly disguised masochists who make an identity out of childish rebellion.

They are collectivists by nature because the axis of their argument excludes all individual behavior and only looks at the ends, not the means. Because they rely on collective guilt they also easily slip on the mask of fascism and totalitarianism. The antithesis (read: antidote) to their opposite political philosophy, which makes a complete mockery of Marx's ideas, is libertarianism.