The Decree on the church’s missionary activity presupposes the dogmatic constitution on The Church and the pastoral constitution ‘The Church in the Modern World’.
It differs from both of these in that they speak of the ‘mission of the church in its total sense of preaching the gospel in word, sacrament, witness and service to the whole human community, Christians and non-Christians alike, whereas this decree is concerned with one important aspect of that total mission, namely, ‘evangelisation and the planting of the church among those peoples and groups where it has not yet taken root (n. 6). The distinction is between ‘the mission of the church’ and ‘the missions’.
The decree does not restrict the vision to the de-Christianised West. The gospel is to penetrate Asia, Africa and Oceania as well.
But wherever missionaries go, they are not to impose an alien cultural reality from outside. They are to recognise and preserve ‘whatever truth and grace are to be found among the nations, as a sort of secret presence of God … and so, whatever good is found to be sown in the hearts and minds of men and women, or in the rites and cultures peculiar to various peoples, is not lost’ (n. 9).
This pastoral principle is rooted in the theological principle of the Incarnation (n. 10). Finally, ‘the whole church is missionary and the work of evangelisation is a basic duty of the People of God (n. 35).