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.
Source: Deus Caritas Est (Vatican.va)