14 No less serious or useful is the work which Catholic missionaries, animated by the spirit which the Church inspires in them, bring to distant, uncivilized countries. Several European rulers have in our time begun to establish colonies there. The German government also seeks to establish colonies, increase its possessions, and open new avenues to commerce and industry. What will make its reputation among the nations is its effort to civilize the savage tribes. But to conciliate the minds and to win the confidence of these uncivilized nations, they should teach them the salutary precepts of religion right from the beginning. They should bring them to understand the true notion of what is just and honest. Finally they should explain what it means to be children of God, for they too have been called to this, thanks to the merits of Our Saviour. This is what the popes had in mind when they sent so many missionaries to barbarian nations. This is certainly not the affair of armies, nor of civil magistrates, nor of conquerors, although they may certainly reap abundant fruit for it. Rather, as history attests, it is the task of those men who go forth from the camp of the Church, embracing the labours and dangers of missionary expeditions. These men do not fear to travel among barbarian nations as messengers and interpreters of God, ready to pour out their blood and their lives for the salvation of their brothers.
Source: Iampridem (Vatican.va)