[Augustine] insists that love is the basis of [all human] society; even in their wars men are in fact seeking peace. But peace is only possible where there is order, and order depends on proper government; but government in which one is subordinated to another is only right is the one who is called to govern does so for the sake of those he governs - as their servant. The motive power of order is therefore love... Love, not natural justice, is what holds even the earthly commonwealth together... love creates order first in the family and among neighbours and then, by extension, in the city and the nation... Faith working through love is the foundation of justice, and without justice there is no commonwealth.
Lesslie Newbigin, Foolishness to the Greeks: The Gospel and Western Culture (Eerdmans, 1986): 103-4.