Pope Paul VI: Ten years after the close of the Second Vatican Council, in 1975 he issued Evangelii Nuntiandi in which the pope stated that the Church "exists in order to evangelize, that is to say in order to preach and teach, to be the channel of the gift of grace, to reconcile sinners with God, and to perpetuate Christ's sacrifice in the Mass, which is the memorial of his death and glorious Resurrection." Pope Paul VI explained the process of evangelizing and that there were two groups that needed to be focused on, those of whom haven't have never heard the Gospel (ad gentes) and those faithful who have left or are no longer practicing the faith.
Bl. Pope John Paul II: "No believer in Christ, no institution of the Church can avoid this supreme duty: to proclaim Christ to all peoples." Blessed John Paul made evangelization the focus of his pontificate saying,
"Evangelization occurs most effectively when the Church engages the culture of those she evangelizes." He wrote an encyclical Redemptoris Missio, in which he provided the three circumstances in evangelization: (1) preaching to those who have never heard the Gospel (ad gentes), (2) preaching to those Christian communities where the Church is present and who have fevor in their faith, and (3) preaching to those Christian communities who have ancient roots but who "have lost a living sense of the faith, or even no longer consider htemselves members of hte Church and live a life far removed from Christ and his Gospel......"
For Bl. John Paul II, One's vocation to holiness is strengthened through the gifts of the Church, namely the grace of hte sacraments, prayer, Scripture, and the Church's teachings and traditions.
Pope Benedict XVI and the future of the New Evangelization:
Secularization has caused a serious crisis for the faithful, not to mention how much harder it will be to evangelize those still waiting to learn of the Gospel. In 2010, the pontiff established the Pontifical Council for the Promotion of the New Evangelization to help promote the unchanged mission of the Church against the cultural secularization confronting man and the Church. The pope noted that the Church is being challenged by "an abandonment of the faith -- a phenomenon progressively more manifest in societies and cultures which for centuries seemed to be permeated by the Gospel. The New Evangelization is not a single formula meant for all circumstances; first and foremost, it is a personal "profound experience of God."