Caritas in Veritate - Encyclical - Pope Benedict XVI - Part 4.
The more we strive to secure a common good corresponding to the real needs of our neighbours, the more effectively we love them. Every Christian is called to practise this charity, in a manner corresponding to his vocation and according to the degree of influence he wields in the pólis. This is the institutional path — we might also call it the political path — of charity, no less excellent and effective than the kind of charity which encounters the neighbour directly, outside the institutional mediation of the pólis. When animated by charity, commitment to the common good has greater worth than a merely secular and political stand would have. Like all commitment to justice, it has a place within the testimony of divine charity that paves the way for eternity through temporal action. Man's earthly activity, when inspired and sustained by charity, contributes to the building of the universal city of God, which is the goal of the history of the human family. In an increasingly globalized society, the common good and the effort to obtain it cannot fail to assume the dimensions of the whole human family, that is to say, the community of peoples and nations, in such a way as to shape the earthly city in unity and peace, rendering it to some degree an anticipation and a prefiguration of the undivided city of God.