“For the Church, evangelizing means bringing the Good News into all the strata of humanity, and through its influence transforming humanity from within and making it new: 'Now I am making the whole of creation new.' But there is no new humanity if there are not first of all new persons renewed by Baptism, and by lives lived according to the Gospel. The purpose of evangelization is therefore precisely this interior change, and if it had to be expressed in one sentence the best way of stating it would be to say that the Church evangelizes when she seeks to convert, solely through the divine power of the message she proclaims, both the personal and collective consciences of people, the activities in which they engage, and the lives and concrete milieu which are theirs.
Without repeating everything that we have already mentioned, it is appropriate first of all to emphasize the following point: for the Church, the first means of evangelization is the witness of an authentically Christian life, given over to God in a communion that nothing should destroy and at the same time given to one's neighbor with limitless zeal. As we said recently to a group of lay people, 'Modern man listens more willingly to witnesses than to teachers, and if he does listen to teachers, it is because they are witnesses.' St. Peter expressed this well when he held up the example of a reverent and chaste life that wins over even without a word those who refuse to obey the word. It is therefore primarily by her conduct and by her life that the Church will evangelize the world, in other words, by her living witness of fidelity to the Lord Jesus- the witness of poverty and detachment, of freedom in the face of the powers of this world, in short, the witness of sanctity.
It is also not superfluous to emphasize the importance and necessity of preaching. 'And how are they to believe in him of whom they have never heard? And how are they to hear without a preacher?... So faith comes from what is heard and what is heard comes by the preaching of Christ.' This law once laid down by the Apostle Paul maintains its full force today.
Preaching, the verbal proclamation of a message, is indeed always indispensable...The fatigue produced these days by so much empty talk and the relevance of many other forms of communication must not however diminish the permanent power of the word, or cause a loss of confidence in it. The word remains ever relevant, especially when it is the bearer of the power of God. This is why St. Paul's axiom, 'Faith comes from what is heard,' also retains its relevance: it is the Word that is heard which leads to belief."
– Pope Paul VI, Evangelii Nuntiandi