88 Christians should cooperate willingly and wholeheartedly in establishing an international order that includes a genuine respect for all freedoms and amicable brotherhood between all. This is all the more pressing since the greater part of the world is still suffering from so much poverty that it is as if Christ Himself were crying out in these poor to beg the charity of the disciples. Do not let men, then, be scandalized because some countries with a majority of citizens who are counted as Christians have an abundance of wealth, whereas others are deprived of the necessities of life and are tormented with hunger, disease, and every kind of misery. The spirit of poverty and charity are the glory and witness of the Church of Christ. Those Christians are to be praised and supported, therefore, who volunteer their services to help other men and nations. Indeed, it is the duty of the whole People of God, following the word and example of the bishops, to alleviate as far as they are able the sufferings of the modern age. They should do this too, as was the ancient custom in the Church, out of the substance of their goods, and not only out of what is superfluous. The procedure of collecting and distributing aids, without being inflexible and completely uniform, should nevertheless be carried on in an orderly fashion in dioceses, nations, and throughout the entire world. Wherever it seems convenient, this activity of Catholics should be carried on in unison with other Christian brothers. For the spirit of charity does not forbid, but on the contrary commands that charitable activity be carried out in a careful and orderly manner. Therefore, it is essential for those who intend to dedicate themselves to the services of the developing nations to be properly trained in appropriate institutes.
Source: Gaudium et Spes (Vatican.va)