Christian realism is a political theology in the Christian tradition. It is built on three biblical presumptions: the sinfulness of humanity, the freedom of humanity, and the validity and seriousness of the Great Commandment. The key political concepts of Christian realism are balance of power and political responsibility. This political-theological perspective is most closely associated with the work of the 20th-century American theologian and public intellectual Reinhold Niebuhr. Niebuhr argued that the Kingdom of God cannot be realized on earth because of the innately corrupt tendencies of society. Due to the injustices that arise among people, we must be willing to compromise the ideal of Kingdom of Heaven on earth. Niebuhr argued that human perfectibility was an illusion, highlighting the sinfulness of humanity at a time when the world was confronted by labor disputes and race riots in industrial hubs like Detroit, Michigan where he pastored, the horrors of the Second World War, the Communist and Fascist totalitarian regimes, and the Holocaust. Christian realism was in part a reaction to the 20th-century Social Gospel movement. Numerous American political figures have been influenced by Christian realism, among them Barack Obama, Martin Luther King Jr., and Jimmy Carter. Augustine of Hippo as the first great Christian realist Niebuhr and his colleagues thought of themselves as following a Christian tradition that had its roots in the Hebrew prophets and later took shape in Christian theology. Augustine of Hippo is generally regarded as the first great Christian realist. Niebuhr commented that Augustine "deserves this distinction because his picture of social reality in his civitas dei gives an adequate account of the social factions, tensions, and competitions which we know to be well-nigh universal on every level of community." Through his reflections on how the two cities are related, Augustine understood how Christian hope could lead to human responsibility for the problems in the present world. To him, Christians are on pilgrimage or in exile awaiting God's kingdom, but it is the certainty of God's ultimate judgment that provides the basis for Christians to bear their responsibility in the present world. Christians are therefore not spectators. They are called to fully involve in this world with a moral life, while at the same time maintaining that they are freed from worldly pursuits to focus on contributions to the common good. Problems in the present world should be taken seriously, even though Augustine had relatively low