Gaudium et Spes §42

⁴² The union of the human family is greatly fortified and fulfilled by the unity, founded on Christ, of the family of God's sons. Christ, to be sure, gave His Church no proper mission in the political, economic or social order. The purpose which He set before her is a religious one. But out of this religious mission itself come a function, a light and an energy which can serve to structure and consolidate the human community according to the divine law. As a matter of fact, when circumstances of time and place produce the need, she can and indeed should initiate activities on behalf of all men, especially those designed for the needy, such as the works of mercy and similar undertakings. The Church recognizes that worthy elements are found in today's social movements, especially an evolution toward unity, a process of wholesome socialization and of association in civic and economic realms. The promotion of unity belongs to the innermost nature of the Church, for she is, "thanks to her relationship with Christ, a sacramental sign and an instrument of intimate union with God, and of the unity of the whole human race." Thus she shows the world that an authentic union, social and external, results from a union of minds and hearts, namely from that faith and charity by which her own unity is unbreakably rooted in the Holy Spirit. For the force which the Church can inject into the modern society of man consists in that faith and charity put into vital practice, not in any external dominion exercised by merely human means. Moreover, since in virtue of her mission and nature she is bound to no particular form of human culture, nor to any political, economic or social system, the Church by her very universality can be a very close bond between diverse human communities and nations, provided these trust her and truly acknowledge her right to true freedom in fulfilling her mission. For this reason, the Church admonishes her own sons, but also humanity as a whole, to overcome all strife between nations and race in this family spirit of God's children, an in the same way, to give internal strength to human associations which are just. With great respect, therefore, this council regards all the true, good and just elements inherent in the very wide variety of institutions which the human race has established for itself and constantly continues to establish. The council affirms, moreover, that the Church is willing to assist and promote all these institutions to the extent that such a service depends on her and can be associated with her mission. She has no fiercer desire than that in pursuit of the welfare of all she may be able to develop herself freely under any kind of government which grants recognition to the basic rights of person and family, to the demands of the common good and to the free exercise of her own mission.