Cardinal George Pell opened the World Youth Day celebrations in Sydney today with a call to not just to the young people who were there to open their hearts to the Spirit but to all those, young and old, who are lost or in despair.

During the opening Mass in Barangaroo, where hundreds and thousands of young people gathered to celebrate the official beginning of the 23rd World Youth Day, Cardinal Pell opened his homily by citing the parable of the shepherd with the 99 sheep, who went in search of the one sheep that was missing. He called the pilgrims who took part in the Mass the sheep that had already been found.

"I begin by encouraging anyone anywhere who regards themselves as already lost and in despair," he said. Christ is still calling to those who are suffering and in need of healing, he said, not just the faithful, but especially those without religion. Cardinal Pell said the causes of the wounds, be they the emptiness of success, family breakdown, drugs or loneliness were secondary because Christ was calling to all those who were suffering "home to love, healing and community".

Drawing on the reading from Ezekiel (37:1-14), he said that the valley of dry bones should be read as a symbol of hope "for those who say our hope is gone, we are as good as dead. This is never true, as long as we can choose". He said: "As long as we live, there is always hope."

The cardinal then addressed the pilgrims directly, using the parable of the seeds which had been the Gospel reading (Luke 8:4-14) and said that most of those who were present were probably those seeds who had found the furrows but some were those in danger of choking with the weeds of the worries of day to day life.

Cardinal Pell called the young not to sit on the fence or to inhabit no man's land but to open themselves to God and to trust in God. He asked them to pray for an openness of heart, saying that "God will not fail us".

He described the pilgrims as the apostles who had come to the ends of the earth to witness Christ's teaching. Many young people found their vocations at World Youth Day, he said. He also said that he hoped the pilgrims would feel their spirits rise in the next five days and urged them to celebrate the rejuvenation of the faith which called them to open their hearts to the spirit. But he warned the young people not to let their enthusiasm make them "forget to listen and to pray".

At the beginning of the Mass Cardinal Pell greeted the pilgrims in the four official languages of World Youth Day: German, French, Spanish and Italian. He especially thanked the Bishop of Cologne for the support and friendship that the Germans had extended them during the last World Youth Day in 2006. The bishops and cardinals from around the world were vested in red and the Mass was celebrated predominantly in English but the Liturgy of the Word was held in Spanish, French and Italian. The Our Father was in Latin.

During the Gospel Procession, Torres Strait Aborigines danced in front of the Sanctuary as two young people from the Torres Straight brought the Gospel up to them. Together with the young Aborigines, they then presented the Gospel to a deacon in a red dalmatic.