In this paper, I seek to flesh out Augustine’s claim in De Civitate Dei XIX.21 that piety is the cause of justice and idolatry the cause of injustice amongst men. Tracing out Augustine’s development of the character of the two cities, I argue that Augustine presents idolatria as the inversion of latreia—as a fragmentation of its participation in and reflection of the Triune fellowship. Latreia, Augustine writes in book X, is the service pertaining to the worship of God encapsulated in love of God and neighbour. In this service, the self, the other, and God are brought into a harmonious relationship that echoes the Triune bond at the same time as it draws the self and the other into a deeper participation in the Trinitarian fellowship itself. The harmony between the self and the other, however, becomes necessarily destabilized when it is uprooted from its foundation in God. In considering Augustine’s portrayal of Satan, Cain and the theurgists described by Hermes Trismegistus in De Civitate Dei, I find three modes of idolatria that fragment what is united in latreia: superbia, cupiditas, and idolatriaproperly understood. I then consider the relationship between these modes, their affect on human relationality and their destruction of the political community, returning to the original point of investigation: why Augustine suggests that idolatria is the cause of injustice in human communities.