"You are the Christ, the Son of the living God". Jesus answers Peter's inspired profession of faith: "You are Peter, and on this rock I will build my Church, and the powers of death shall not prevail against it. I will give you the keys of the Kingdom of Heaven".
This is the first time that Jesus speaks of the Church, whose mission is the actuation of God's great design to gather the whole of humanity into a single family in Christ. Peter's mission, and that of his Successors, is precisely to serve this unity of the one Church of God formed of Jews and pagans of all peoples; his indispensable ministry is to ensure that she is never identified with a single nation, with a single culture, but is the Church of all peoples...God's peace and the renewing power of his love.
This, then, is the special mission of the Pope, Bishop of Rome and Successor of Peter: to serve the inner unity that comes from God's peace, the unity of those who have become brothers and sisters in Jesus Christ.
Pope Benedict XVI
Angelus
24 August 2008