We saw in Plato a functional notion of the social good. Justice is the proper functioning of a society, where each plays the appropriate role and no one interferes with anyone else. Christian political philosophy was of two minds. Augustine typifies the attitude that the community of the church and state constitute two entirely separate realms. The opposite view is that the state should be a theocracy, in which the laws of the state are the laws of God.
Theocracies can flourish only when there is a considerable unity of religious thinking.
With the Reformation and the breakup of the Roman Catholic Church, the close connection between church and state began to be torn asunder. Deadly religious wars were fought across the European continent. Hobbes returned to human nature as the basis of the state, but the nature he found was quite different from that discussed by Plato, Aristotle and most of the other Greek philosophers. Reason, formerly arbiter of the good, now becomes a mere calculating device, no different in principle from a computer. Material man has as his end merely the preservation and promotion of his own existence.