The Pope made that observation Saturday when meeting with faithful from four parishes of the eastern outskirts of Rome.
The parish communities of St. Maximilian Kolbe, St. Patrick, St. Margaret Mary Alacoque and St. Mary Mediatrix lack essential services, the Holy Father noted.
"Despite the precariousness of the structures" in their parishes, he invited the 10,000 people gathered in Paul VI Hall to redouble the "constant effort of evangelization."
"Be open and hospitable parish communities," he said. He noted the numerous Latin American and Polish immigrants in those neighborhoods.
"May these brothers and sisters of ours feel loved as Christ loved and as he served every man and woman to the sacrifice of himself," the Pope said. "This is the concrete testimony of faith that touches the heart, including of those known to be fallen away."
The Pope invited the young people present to participate in World Youth Day, which will be observed at the diocesan level in Rome with two events: a vigil, on April 1 in St. Peter's Square, and Palm Sunday Mass, also in the square. The Holy Father will preside over both events.
"Find in Christ crucified and resurrected the courage to evangelize our world, so tried by divisions, hatreds, wars, terrorism, but full of human and spiritual resources," the Pontiff told his young listeners.
John Paul II thus continued with his meetings with parishes of his diocese, to which he committed himself at the start of his pontificate. To spare the Pope extra strain, the parish communities now come to visit him in the Vatican.