-- Lk 10:1-12
The origin and purpose of mission. The Lord's missionary mandate is ultimately grounded in the eternal love of the Most Holy Trinity: "The Church on earth is by her nature missionary since, according to the plan of the Father, she has as her origin the mission of the Son and the Holy Spirit." The ultimate purpose of mission is none other than to make men share in the communion between the Father and the Son in their Spirit of love.
-- CCC 850
By her very mission, "the Church . . . travels the same journey as all humanity and shares the same earthly lot with the world: she is to be a leaven and, as it were, the soul of human society in its renewal by Christ and transformation into the family of God." Missionary endeavor requires patience. It begins with the proclamation of the Gospel to peoples and groups who do not yet believe in Christ, continues with the establishment of Christian communities that are "a sign of God's presence in the world," and leads to the foundation of local churches. It must involve a process of inculturation if the Gospel is to take flesh in each people's culture. There will be times of defeat. "With regard to individuals, groups, and peoples it is only by degrees that [the Church] touches and penetrates them and so receives them into a fullness which is Catholic."
-- CCC 854