27. It must be admitted that the Church's leadership was slow to realize that the issue of the just structuring of society needed to be approached in a new way. There were some pioneers, such as Bishop Ketteler of Mainz († 1877), and concrete needs were met by a growing number of groups, associations, leagues, federations and, in particular, by the new religious orders founded in the nineteenth century to combat poverty, disease and the need for better education. In 1891, the papal magisterium intervened with the Encyclical Rerum Novarum of Leo XIII. This was followed in 1931 by Pius XI's Encyclical Quadragesimo Anno. In 1961 Blessed John XXIII published the Encyclical Mater et Magistra, while Paul VI, in the Encyclical Populorum Progressio (1967) and in the Apostolic Letter Octogesima Adveniens (1971), insistently addressed the social problem, which had meanwhile become especially acute in Latin America. My great predecessor John Paul II left us a trilogy of social Encyclicals: Laborem Exercens (1981), Sollicitudo Rei Socialis (1987) and finally Centesimus Annus (1991). Faced with new situations and issues, Catholic social teaching thus gradually developed, and has now found a comprehensive presentation in the Compendium of the Social Doctrine of the Church published in 2004 by the Pontifical Council Iustitia et Pax. Marxism had seen world revolution and its preliminaries as the panacea for the social problem: revolution and the subsequent collectivization of the means of production, so it was claimed, would immediately change things for the better. This illusion has vanished. In today's complex situation, not least because of the growth of a globalized economy, the Church's social doctrine has become a set of fundamental guidelines offering approaches that are valid even beyond the confines of the Church: in the face of ongoing development these guidelines need to be addressed in the context of dialogue with all those seriously concerned for humanity and for the world in which we live.
28. In order to define more accurately the relationship between the necessary commitment to justice and the ministry of charity, two fundamental situations need to be considered:
a) 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?”. 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. 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.
Here politics and faith meet. Faith by its specific nature is an encounter with the living God—an encounter opening up new horizons extending beyond the sphere of reason. But it is also a purifying force for reason itself. From God's standpoint, faith liberates reason from its blind spots and therefore helps it to be ever more fully itself. Faith enables reason to do its work more effectively and to see its proper object more clearly. This is where Catholic social doctrine has its place: it has no intention of giving the Church power over the State. Even less is it an attempt to impose on those who do not share the faith ways of thinking and modes of conduct proper to faith. Its aim is simply to help purify reason and to contribute, here and now, to the acknowledgment and attainment of what is just.
The Church's social teaching argues on the basis of reason and natural law, namely, on the basis of what is in accord with the nature of every human being. It recognizes that it is not the Church's responsibility to make this teaching prevail in political life. Rather, the Church wishes to help form consciences in political life and to stimulate greater insight into the authentic requirements of justice as well as greater readiness to act accordingly, even when this might involve conflict with situations of personal interest. Building a just social and civil order, wherein each person receives what is his or her due, is an essential task which every generation must take up anew. As a political task, this cannot be the Church's immediate responsibility. Yet, since it is also a most important human responsibility, the Church is duty-bound to offer, through the purification of reason and through ethical formation, her own specific contribution towards understanding the requirements of justice and achieving them politically.
The Church cannot and must not take upon herself the political battle to bring about the most just society possible. She cannot and must not replace the State. Yet at the same time she cannot and must not remain on the sidelines in the fight for justice. She has to play her part through rational argument and she has to reawaken the spiritual energy without which justice, which always demands sacrifice, cannot prevail and prosper. A just society must be the achievement of politics, not of the Church. Yet the promotion of justice through efforts to bring about openness of mind and will to the demands of the common good is something which concerns the Church deeply.
b) Love—caritas—will always prove necessary, even in the most just society. There is no ordering of the State so just that it can eliminate the need for a service of love. Whoever wants to eliminate love is preparing to eliminate man as such. There will always be suffering which cries out for consolation and help. There will always be loneliness. There will always be situations of material need where help in the form of concrete love of neighbour is indispensable. The State which would provide everything, absorbing everything into itself, would ultimately become a mere bureaucracy incapable of guaranteeing the very thing which the suffering person—every person—needs: namely, loving personal concern. We do not need a State which regulates and controls everything, but a State which, in accordance with the principle of subsidiarity, generously acknowledges and supports initiatives arising from the different social forces and combines spontaneity with closeness to those in need. The Church is one of those living forces: she is alive with the love enkindled by the Spirit of Christ. This love does not simply offer people material help, but refreshment and care for their souls, something which often is even more necessary than material support. In the end, the claim that just social structures would make works of charity superfluous masks a materialist conception of man: the mistaken notion that man can live “by bread alone” (Mt 4:4; cf. Dt 8:3)—a conviction that demeans man and ultimately disregards all that is specifically human.
29. We can now determine more precisely, in the life of the Church, the relationship between commitment to the just ordering of the State and society on the one hand, and organized charitable activity on the other. We have seen that the formation of just structures is not directly the duty of the Church, but belongs to the world of politics, the sphere of the autonomous use of reason. The Church has an indirect duty here, in that she is called to contribute to the purification of reason and to the reawakening of those moral forces without which just structures are neither established nor prove effective in the long run.
The direct duty to work for a just ordering of society, on the other hand, is proper to the lay faithful. As citizens of the State, they are called to take part in public life in a personal capacity. So they cannot relinquish their participation “in the many different economic, social, legislative, administrative and cultural areas, which are intended to promote organically and institutionally the common good.”  The mission of the lay faithful is therefore to configure social life correctly, respecting its legitimate autonomy and cooperating with other citizens according to their respective competences and fulfilling their own responsibility. Even if the specific expressions of ecclesial charity can never be confused with the activity of the State, it still remains true that charity must animate the entire lives of the lay faithful and therefore also their political activity, lived as “social charity”.
The Church's charitable organizations, on the other hand, constitute an opus proprium, a task agreeable to her, in which she does not cooperate collaterally, but acts as a subject with direct responsibility, doing what corresponds to her nature. The Church can never be exempted from practising charity as an organized activity of believers, and on the other hand, there will never be a situation where the charity of each individual Christian is unnecessary, because in addition to justice man needs, and will always need, love.