The just ordering of society and the State is a central responsibility of politics. As Augustine once said, a State which is not governed according to justice would be just a bunch of thieves: “Remota itaque iustitia quid sunt regna nisi magna latrocinia?”.[18] Fundamental to Christianity is the distinction between what belongs to Caesar and what belongs to God (cf. Mt 22:21), in other words, the distinction between Church and State, or, as the Second Vatican Council puts it, the autonomy of the temporal sphere.[19] The State may not impose religion, yet it must guarantee religious freedom and harmony between the followers of different religions. For her part, the Church, as the social expression of Christian faith, has a proper independence and is structured on the basis of her faith as a community which the State must recognize. The two spheres are distinct, yet always interrelated.
Justice is both the aim and the intrinsic criterion of all politics. Politics is more than a mere mechanism for defining the rules of public life: its origin and its goal are found in justice, which by its very nature has to do with ethics. The State must inevitably face the question of how justice can be achieved here and now. But this presupposes an even more radical question: what is justice? The problem is one of practical reason; but if reason is to be exercised properly, it must undergo constant purification, since it can never be completely free of the danger of a certain ethical blindness caused by the dazzling effect of power and special interests. – from Deus Caritas Est
