Pope John Paul II
Redemptoris Missio §20
Redemptoris Missio: On the Permanent Validity of the Church's Missionary Mandate
20 The Church is effectively and concretely at the service of the kingdom. This is seen especially in her preaching, which is a call to conversion. Preaching constitutes the Church's first and fundamental way of serving the coming of the kingdom in individuals and in human society. Eschatological salvation begins even now in newness of life in Christ: "To all who believed in him, who believed in his name, he gave power to become children of God" (Jn 1:12). The Church, then, serves the kingdom by establishing communities and founding new particular churches, and by guiding them to mature faith and charity in openness toward others, in service to individuals and society, and in understanding and esteem for human institutions. The Church serves the kingdom by spreading throughout the world the "gospel values" which are an expression of the kingdom and which help people to accept God's plan. It is true that the inchoate reality of the kingdom can also be found beyond the confines of the Church among peoples everywhere, to the extent that they live "gospel values" and are open to the working of the Spirit who breathes when and where he wills (cf. Jn 3:8). But it must immediately be added that this temporal dimension of the kingdom remains incomplete unless it is related to the kingdom of Christ present in the Church and straining towards eschatological fullness. The many dimensions of the kingdom of God do not weaken the foundations and purposes of missionary activity, but rather strengthen and extend them. The Church is the sacrament of salvation for all mankind, and her activity is not limited only to those who accept her message. She is a dynamic force in mankind's journey toward the eschatological kingdom, and is the sign and promoter of gospel values. The Church contributes to mankind's pilgrimage of conversion to God's plan through her witness and through such activities as dialogue, human promotion, commitment to justice and peace, education and the care of the sick, and aid to the poor and to children. In carrying on these activities, however, she never loses sight of the priority of the transcendent and spiritual realities which are premises of eschatological salvation. Finally, the Church serves the kingdom by her intercession, since the kingdom by its very nature is God's gift and work, as we are reminded by the gospel parables and by the prayer which Jesus taught us. We must ask for the kingdom, welcome it and make it grow within us; but we must also work together so that it will be welcomed and will grow among all people, until the time when Christ "delivers the kingdom to God the Father" and "God will be everything to everyone" (cf. 1 Cor 15:24, 28).
Source: Redemptoris Missio (Vatican.va)