From Pope St. John Paul II’s encyclical Veritatis Splendor (1993):
Evangelization is the most powerful and stirring challenge which the Church has been called to face from her very beginning. Indeed, this challenge is posed not so much by the social and cultural milieux which she encounters in the course of history, as by the mandate of the Risen Christ, who defines the very reason for the Church’s existence: “Go into all the world and preach the Gospel to the whole creation” (Mk 16:15).
At least for many peoples, however, the present time is instead marked by a formidable challenge to undertake a “new evangelization”, a proclamation of the Gospel which is always new and always the bearer of new things, an evangelization which must be “new in its ardour, methods and expression”.166 Dechristianization, which weighs heavily upon entire peoples and communities once rich in faith and Christian life, involves not only the loss of faith or in any event its becoming irrelevant for everyday life, but also, and of necessity, a decline or obscuring of the moral sense. This comes about both as a result of a loss of awareness of the originality of Gospel morality and as a result of an eclipse of fundamental principles and ethical values themselves. Today’s widespread tendencies towards subjectivism, utilitarianism and relativism appear not merely as pragmatic attitudes or patterns of behaviour, but rather as approaches having a basis in theory and claiming full cultural and social legitimacy.
166 Address to the Bishops of CELAM (March 9,1983), III: Insegnamenti, VI, 1 (1983), 698.
— Veritatis Splendor 106