Pope Benedict XVI admitted Sunday that cases of child abuse by paedophile priests had undermined the Roman Catholic Church's credibility in Ireland.
"They abused people and undermined the credibility of the Church's message," he said in a message on the final day of the 50th International Eucharistic Congress held in Dublin.
"Thankfulness and joy at such a great history of faith and love have recently been shaken in an appalling way by the revelation of sins committed by priests and consecrated persons against people entrusted to their care," the pope added.
"How are we to explain the fact that people who regularly received the Lord's body and confessed their sins in the sacrament of penance have offended in this way?"
The pope's envoy to the Catholic festival earlier this week apologised to victims of child sex abuse by priests after meeting with a group of them for two hours to hear about the abuse they suffered and the impact it had on them.
Ireland, a predominantly Roman Catholic country, has been rocked in recent years by the findings of a series of unprecedented state inquiries into child abuse by paedophile priests and attempts by Church leaders to cover them up.