41 Laymen cooperate in the Church's work of evangelization; as witnesses and at the same time as living instruments, they share in her saving mission; especially if they have been called by God and have been accepted by the bishop for this work. In those lands which are already Christian, laymen cooperate in the work of evangelization by nurturing in themselves and in others a knowledge and love of the missions; by stimulating vocations in their own family, in Catholic associations, and in the schools; by offering subsidies of every kind, that they may offer to others that gift of Faith which they have received gratis. But in mission lands, let laymen, whether foreigners or autochthonous, teach in schools, administer temporal goods cooperate in parish and diocesan activities, and organize and promote various forms of the lay apostolate, in order that the faithful of the young churches may be able to take part as soon as possible in the life of the Church. Lastly, let laymen gladly offer socio - economic cooperation to peoples on the way of development. This cooperation is all the more to be praised, the more it concerns itself with founding institutes which touch on the basic structures of social life, or which are oriented to the training of those who bear the responsibility for the government. Worthy of special praise are those laymen who, in universities or in scientific institutes, promote by their historical and scientific religious research the knowledge of peoples and of religions; thus helping the heralds of the Gospel, and preparing for the dialogue with non - Chistians. They should cooperate in a brotherly spirit with other Christians, with non - Christians, and with members of international organizations, aways having before their eyes the fact that "the building up of the earthly city should have its foundation in the Lord, and should be directed towards Him." To be equal to all these tasks, laymen need the necessary technical and spiritual preparation, which should be given in institutes destined for this; so that their lives may be a witness for Christ among non - Christians, according to the words of the Apostle: "Do not be a stumbling - block to Jews and Greeks and to the Church of God, even as I myself in all things please all men, not seeking what is profitable to myself but to the many, that they may be saved." (1 Cor. 10:32-33).
Source: Ad Gentes (Vatican.va)