The Holy Father reminded the young pilgrims that to truly be Christian, one needs to be united with Christ in his Church.  “We cannot follow Jesus on our own,” he said.

Dear young friends, as the Successor of Peter, let me urge you to strengthen this faith which has been handed down to us from the time of the Apostles. Make Christ, the Son of God, the centre of your life. But let me also remind you that following Jesus in faith means walking at his side in the communion of the Church. We cannot follow Jesus on our own. Anyone who would be tempted to do so “on his own”, or to approach the life of faith with that kind of individualism so prevalent today, will risk never truly encountering Jesus, or will end up following a counterfeit Jesus.

Having faith means drawing support from the faith of your brothers and sisters, even as your own faith serves as a support for the faith of others. I ask you, dear friends, to love the Church which brought you to birth in the faith, which helped you to grow in the knowledge of Christ and which led you to discover the beauty of his love. Growing in friendship with Christ necessarily means recognizing the importance of joyful participation in the life of your parishes, communities and movements, as well as the celebration of Sunday Mass, frequent reception of the sacrament of Reconciliation, and the cultivation of personal prayer and meditation on God’s word.

— Pope Benedict XVI, homily during the closing Mass of World Youth Day, 21 August 2011

Full text here.