Tribal conflict ideologies represent a serious challenge for liberal democracies, and none more so than various neo-Marxist theories in ascendancy today. Whereas liberal democracy is based on Enlightenment principles assuming that rational and pragmatic considerations by individuals will produce gradual social progress, Marxism is a collectivist tribal ideology that insists on the inevitability of social conflict and revolution to bring about change. This chapter surveys the origins and defining features of Marxist and neo-Marxist tribal ideologies. The psychological mechanisms that are responsible for the enduring attraction of Marxist ideology are discussed and that appeal to people’s evolutionary propensity to seek simplicity, epistemic certainty, positive group identity, moral absolutism, and utopistic idealism in tribal narratives. The strategies employed by populist tribal movements to gratify the psychological expectations of their followers are reviewed, and the reasons for the alarming spread of neo-Marxist movements are considered.