 Augustine’s City of God is not a treatise of political or social philosophy. It is an extended plea designed to persuade people “to enter the city of God or to persist in it” (Letter 2*.3). The criterion of membership in the city of God (a metaphor Augustine takes from the Psalms, cf. Psalm 86:3 quoted, e.g., in De civitate dei 11.1) and its antagonist, the earthly city, is right or wrong love.  A person belongs to the city of God if and only if he directs his love towards God even at the expense of self-love, and he belongs to the earthly city or city of the devil if and only if he postpones love of God for self-love, proudly making himself his greatest good (De civitate dei 14.28). The main argument of the work is that true happiness, which is sought by every human being (ib. 10.1),  cannot be found outside the city of God founded by Christ (cf. ib. 1, prologue). The first ten books deconstruct, in a manner reminiscent of traditional Christian apologetics, the alternative conceptions of happiness in the Roman political tradition (which equates happiness with the prosperity of the Empire, thus falling prey to evil demons who posed as the defenders of Rome but in fact ruined it morally and politically) and in Greek, especially Platonic, philosophy (which, despite its insight into the true nature of God, failed to accept the mediation of Christ incarnate out of pride and turned to false mediators, i.e., deceptive demons; bks. 8–10 have an interesting disquisition on Platonic demonology). Augustine’s approach in the second, positive half is Scriptural, creationist and eschatological; this fact accounts for the specific character of its historical dimension. The history of the two cities begins with the creation of the world and the defection of the devil and the sin of Adam and Eve (bks. 11–14); it continues with the providentially-governed vicissitudes of the People of Israel (the first earthly representative of the city of God) and, after the coming of Christ, of the Church (bks. 15–17, supplemented by a survey of the concurrent secular history from the earliest Eastern empires to contemporary Rome in bk. 18); and it ends with the final destination (finis, to be understood both ethically as “ultimate goal” and eschatologically as “end of times”) of the two cities in eternal damnation and eternal bliss (bks. 19–22; for the structure and basic ideas of the City of God see O’Daly 1999). To a great extent, Augustine’s approach is exegetical; for him, the history of the city of God is, in substance, sacred history as laid down in Scripture (Markus 1970: 1–21). Obviously, however, the heavenly and earthly cities must not be confounded with the worldly institutions of the church and the state. In history, each of these, and the Church in particular, is a mixed body in which members of the city of God and the earthly city coexist, their distinction being clear only to God, who will separate the two cities at the end of times (ib. 1.35; 10.32 etc.). While the city of God is a stranger or, at best, a resident alien (peregrinus: ib. 15.1; 15.15) in this world and yearns for its celestial homeland, the earthly city is not a unified body at all but lies in continuous strife with itself because it is dominated by lust for power, the most widespread form of the archetypal sin of pride in political and social life (ib. 18.2). All this is in agreement with Augustine’s ideas on predestination and grace;  the history of the two cities is essentially the history of fallen humanity. This dualistic account is however qualified when, in the part of the work that moves closest to social philosophy, Augustine analyzes the attitude a Christian ought to adopt to the earthly society she inevitably lives in during her existence in this world. Starting, again, from the axiom that all human beings naturally desire what is good for them, he innovatively determines the goal that every individual and every community in fact pursues as “peace” (pax), which, in his view, is largely equivalent with natural order and subordination. There are higher and lesser degrees of both individual and collective peace, e.g., the control of the emotions through reason, the subordination of body to soul, the subordination of children to parents in the family or a functioning hierarchical order in the state; at the top is “peace with God” or the subordination of the human mind to God (ib. 19.13; Weissenberg 2005). The lower forms of peace are relative goods and, as such, legitimately pursued as long as they are not mistaken for the absolute good. Political peace and order is sought by members of the city of God and the earthly city alike, but whereas the latter “enjoy” it because it is the greatest good they can attain and conceive of, the former “use” it for the sake of their peace with God, i.e., in order that they and others may enjoy an unhindered Christian religious life (ib. 19.17; 19.26; for “enjoyment” and “use” see  7.1 Happiness).  Political peace is thus morally neutral insofar as it is a goal common to Christians and non-Christians. Augustine criticizes Cicero because he included justice in his definition of the state (Cicero, De re publica 1.39) and thereby gave the earthly state an inherent moral quality that in reality is the privilege of the city of God (De civitate dei 19.21). He himself prefers a more pragmatic definition that makes the consensus about a common object of “love” (i.e., a common good agreed on by all members of the community) the criterion of a state; the moral evaluation is not a matter of the definition but depends on the evaluation of the goal it pursues (cf.  7.3 Love).  The early Roman Empire, which strove for glory, was more tolerable than the Oriental empires that were driven by naked lust for power; the best imaginable goal pursued by an earthly society would be perfect earthly peace (ib. 19.24; Weithman 2001: 243–4). Christians are allowed and even called to work for the well-being of the societies they live in as long as they promote earthly peace for the sake of their citizens’ and their own true happiness; in practice, this will usually mean furthering Christian religion (ib. 5.25–6, on the Christian emperors Constantine and Theodosius; Letter 155.12; 16; Dodaro 2004b; Tornau 2013). But the doctrine of the two cities deliberately precludes any promotion of the emperor or the empire to a providential and quasi-sacred rank. Not even Christians in power will be able to overcome the inherent wretchedness of fallen humanity (De civitate dei 19.6). Like the vast majority of ancient Christian theologians, Augustine has little or no interest in social reform. Slavery, meaning unnatural domination of humans over humans, is a characteristic stain of postlapsarian human life and, at the same time, an evil that is put to good effects when it secures social order (ib. 19.15; Rist 1994: 236–239). War results from sin and is the privileged means of satisfying lust for power (ib. 18.2; 19.7). Nevertheless, Augustine wrote a letter to refute the claim that Christianity advocated a politically impracticable pacifism (Letter 138). His Christian reinterpretation of the traditional Roman Just War Theory should be read in the framework of his general theory of virtue and peace (Holmes 1999). To be truly just according to Augustinian standards, a war would have to be waged for the benefit of the adversary and without any vindictiveness, in short, out of love of neighbor, which, in a fallen world, seems utopian (Letter 138.14). Wars may however be relatively just if they are defensive and properly declared (cf. Cicero, De officiis 1.36–37) or commanded by a just authority even short of the special case of the wars of the People of Israel that were commanded by God himself (Contra Faustum 22.74–78).