CATECHISM OF THE CATHOLIC CHURCH
SECOND EDITION

Paragraphs 852–856

852 Missionary paths. The Holy Spirit is the protagonist, "the principal agent of the whole of the Church's mission." It is he who leads the Church on her missionary paths. "This mission continues and, in the course of history, unfolds the mission of Christ, who was sent to evangelize the poor; so the Church, urged on by the Spirit of Christ, must walk the road Christ himself walked, a way of poverty and obedience, of service and self-sacrifice even to death, a death from which he emerged victorious by his resurrection." So it is that "the blood of martyrs is the seed of Christians."
853 On her pilgrimage, the Church has also experienced the "discrepancy existing between the message she proclaims and the human weakness of those to whom the Gospel has been entrusted." Only by taking the "way of penance and renewal," the "narrow way of the cross," can the People of God extend Christ's reign. For "just as Christ carried out the work of redemption in poverty and oppression, so the Church is called to follow the same path if she is to communicate the fruits of salvation to men."
854 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."
855 The Church's mission stimulates efforts towards Christian unity. Indeed, "divisions among Christians prevent the Church from realizing in practice the fullness of catholicity proper to her in those of her sons who, though joined to her by Baptism, are yet separated from full communion with her. Furthermore, the Church herself finds it more difficult to express in actual life her full catholicity in all its aspects."
856 The missionary task implies a respectful dialogue with those who do not yet accept the Gospel. Believers can profit from this dialogue by learning to appreciate better "those elements of truth and grace which are found among peoples, and which are, as it were, a secret presence of God." They proclaim the Good News to those who do not know it, in order to consolidate, complete, and raise up the truth and the goodness that God has distributed among men and nations, and to purify them from error and evil "for the glory of God, the confusion of the demon, and the happiness of man."