Ad Gentes
27 All these things, though necessary for everyone who is sent to the nations, can scarcely be attained to in reality by individual missionaries. Since even mission work itself, as experience teaches, cannot be accomplished by lone individuals, a common calling has gathered these individuals together into institutes, in which, with united efforts, they are properly trained and might carry out this work in the name of the Church and under the direction of the hierarchy.
For many centuries, these institutes have borne the burden of the day and the heat, devoting themselves to missionary labor either entirely or in part. Often vast territories were committed to them by the Holy See for evangelization, and there they gathered together a new people for God, a local church clinging to their own shepherds. With their zeal and experience, they will serve, by fraternal cooperation either in the care of souls or in rendering special services for the common good, those churches which were founded at the cost of their sweat and even of their blood.
Sometimes, throughout the entire extent of some region, they will take certain tasks upon themselves; e.g., the evangelization of groups of peoples who perhaps for special reasons have not yet accepted the Gospel message, or who have thus far resisted it.[Cf. “Priestly Ministry and Life,” 10, refers to dioceses and personal prelatures and the like.]
If need be, let them be on hand to help and train, out of their own experience, those who will devote themselves to missionary activity for a time.
For these reasons, and since there are still many nations to be led to Christ, the institutes remain extremely necessary.
30 In order that the proper goals and results may be obtained, all missionary workers should have but „one heart and one soul“ (Acts 4:32) in the actual carrying out of mission work itself.
It is the bishop‘s role, as the ruler and center of unity in the diocesan apostolate, to promote missionary activity, to direct it and to coordinate it but always in such a way that the zeal and spontaneity of those who share in the work may be preserved and fostered. All missionaries, even exempt Religious, are subject to his power in the various works which refer to the exercise of the sacred apostolate.
…Moreover let them take care that apostolic activity be not limited to those only who have already been converted. A fair proportion of personnel and funds should be assigned to the evangelization of non–Christians.
39 … Professors in seminaries and universities will teach young people the true state of the world and of the Church, so that the necessity of a more intense evangelization of non – Christians will become clear to them and will nurture their zeal. In teaching the dogmatic, biblical, moral, and historical branches, they should focus attention on the missionary elements therein contained, so that in this way a missionary, awareness may be formed in future priests.
40 … Now since, under the inspiration of the Holy Spirit, secular institutes are daily increasing in the Church, their activity, under the authority of the bishop, could be fruitful in the missions in many ways as a sign of complete dedication to the evangelization of the world.