UNIVERSAL BROTHERHOOD
Sacred Scripture, with which the experience of centuries agrees, teaches mankind that human progress, though a great good for mankind, brings with it a great temptation: for by disrupting the order of values and mixing evil with good, individuals and groups look only to their own things, not to the things of others; and thus the world ceases to be the field of genuine fraternity, while instead the increase of human power threatens to destroy mankind itself........
Therefore, if the question arises as to how such a miserable situation can be overcome, Christians by way of answer affirm that all human activities, which are endangered daily by pride and disordered self-love, must be purified and made perfect through the cross and resurrection of Christ. Redeemed, in fact, by Christ and become a new creature in the Holy Spirit, man can and must also love the things that God has created. From God he receives them, and looks upon them and honours them as if they were presently coming from the hands of God. Of them he thanks the Benefactor and, using and enjoying the creatures in poverty and freedom of spirit, he is introduced into the true possession of the world, as if at the same time he had nothing and possessed everything: "Everything", in fact, "is yours! But you are Christ's, and Christ is God's" (1 Cor 3:22-23).
The Word of God, through whom all things were created, became flesh Himself, and came to dwell on the earth of men, entered into the history of the world as the perfect man, taking this and recapitulating it in Himself. He reveals to us that "God is love" (1 Jn 4:8), and at the same time teaches us that the fundamental law of human perfection, and therefore also of the transformation of the world, is the new commandment of charity. Those, therefore, who believe in divine charity, are made certain by him, that the way of charity is open to all men and that efforts to achieve universal brotherhood are not in vain. So too he admonishes us not to walk the path of charity only in great things, but rather and above all in the ordinary circumstances of life. By bearing death for us all sinners, he teaches us by his example that it is also necessary to bear the cross; that which from the flesh and the world is placed on the shoulders of those who seek peace and justice. By his resurrection constituted Lord, he, the Christ to whom all power in heaven and on earth has been given, still works in the hearts of men by the virtue of his Spirit, not only arousing the desire for the world to come, but also by inspiring, purifying and strengthening those generous intentions by which the family of men seeks to make their lives more human and to subdue the whole earth to this end. But the gifts of the Spirit are various: some he calls to give manifest witness to the heavenly abode with the desire for it, thus helping to keep it alive in humanity; others he calls to consecrate themselves to the service of men on earth, so as to prepare through such their ministry the matter for the kingdom of heaven. In all, however, he works a liberation, so that, through the renunciation of selfishness and the human valorisation of earthly powers, they may be decisively oriented towards that future in which humanity itself will become an acceptable oblation to God. (GS ch III 37-38)
From the Pastoral Constitution 'Gaudium et Spes', Second Vatican Council - 7 December 1965