As you know, among the various documents dealing with Christian unity, there is the Directory for Ecumenism published by the Pontifical Council for Promoting Christian Unity. Ecumenism -- or the search for unity among Christians -- has become in our time an increasingly urgent task for the Catholic Church, as is evident from the growth of intercultural exchange and the challenge of secularism. Consequently, given the rapidly growing number of new Christian denominations, and especially certain forms of often aggressive proselytism, the work of ecumenism has become more complex. In this context, a good historical and doctrinal formation is absolutely essential, so as to foster necessary discernment and lead to a better understanding of the specific identity of each of these communities, the elements that divide them, and those elements that can be helpful on the road to greater unity. The greatest area of common ground for collaboration should be the defence of fundamental moral values -- transmitted by the biblical tradition -- against the relativistic and consumerist cultural forces that seek to destroy them. Another such area is faith in God the Creator and in Jesus Christ his incarnate Son. Moreover, there will always be the principle of fraternal love and the search for mutual understanding and rapprochement. Yet we must also be concerned with defending the faith of our people, confirming them in the joyful certitude that "unica Christi Ecclesia … subsistit in Ecclesia catholica, a successore Petri et Episcopis in eius communione gubernata" ["The one Church of Christ … subsists in the Catholic Church which is governed by the successor of Peter and by the Bishops in communion with him"] ("Lumen Gentium," 8).