3 Peoples everywhere, open the doors to Christ! His Gospel in no way detracts from man's freedom, from the respect that is owed to every culture and to whatever is good in each religion. By accepting Christ, you open yourselves to the definitive Word of God, to the One in whom God has made himself fully known and has shown us the path to himself. The number of those who do not know Christ and do not belong to the Church is constantly on the increase. Indeed, since the end of the Council it has almost doubled. When we consider this immense portion of humanity which is loved by the Father and for whom he sent his Son, the urgency of the Church's mission is obvious. On the other hand, our own times offer the Church new opportunities in this field: we have witnessed the collapse of oppressive ideologies and political systems; the opening of frontiers and the formation of a more united world due to an increase in communications; the affirmation among peoples of the gospel values which Jesus made incarnate in his own life (peace, justice, brotherhood, concern for the needy); and a kind of soulless economic and technical development which only stimulates the search for the truth about God, about man and about the meaning of life itself. God is opening before the Church the horizons of a humanity more fully prepared for the sowing of the Gospel. I sense that the moment has come to commit all of the Church's energies to a new evangelization and to the mission ad gentes . No believer in Christ, no institution of the Church can avoid this supreme duty: to proclaim Christ to all peoples.
Source: Redemptoris Missio (Vatican.va)