Pope Benedict XVI has said it "remains a mystery" that people who regularly "received the Lord’s body and confessed their sins" had committed the offence of child abuse.
In a pre-recorded address to the closing ceremony of the 50th International Eucharistic Congress, which came to an end at Croke Park in Dublin today, the pope said the Church had "been shaken in an appalling way by the revelation of sins committed by priests and consecrated persons against people entrusted to their care".
"Instead of showing them the path towards Christ, towards God, instead of bearing witness to his goodness, they abused people and undermined the credibility of the Church’s message," he said.
The pope said "much still remains to be done on the path of real liturgical renewal".
He also told the congregation that they were among the heirs to a Church that has been a force for good throughout the world, before revealing that the 2016 International Eucharistic Congress will be held in Cebu in the Philippines.
Some 75,000 people are understood to have attended the event. Taoiseach Enda Kenny, President Michael D Higgins and more than 1,000 priests and bishops from around the world were among those in the audience.
The Statio Orbis Liturgy Mass was celebrated by the papal legate, Cardinal Marc Ouellet.
"Faith is the most precious gift we have received with baptism," he said. "Let’s not keep it private and fearful. Let it grow as a splendid tree through sharing everywhere."
Cardinal Ouellet said that after a week of Eucharistic reflection, celebration and adoration, "we are certainly more aware of God’s call to communion with him and with one another".
In his closing address, Archbishop of Dublin Diarmuid Martin said the Eucharist "had awakened in our hearts something which went way beyond our plans and expectations".
"We have experienced the communion of the Church. We have been enriched by our sharing with those who have joined us from over 120 countries," he said.
Archbishop Martin said he hoped pilgrims would "go away with a renewed love of the Church".
"We must go away from here wanting to tell others not just about the Congress, but about Jesus Christ himself who in giving himself in sacrifice revealed to us that God is love. In the Eucharist we are captured into that self-giving love and are empowered to be loving people."
Traffic is likely to be heavy in the north city tonight with management plans in place until about 7pm, with a number of road closures, and motorists have been asked to avoid the area.