Paedophile priests who abused those in their care undermined the credibility of the Catholic Church, Pope Benedict XVI has said.
In a pre-recorded address to almost 80,000 pilgrims in Dublin, the pontiff said the legacy of Irish Catholicism has been shaken by the clerical sexual abuse of children, adding it remained a mystery how clergy could commit such sins.
The Pope told the congregation attending the closing Mass of the 50th International Eucharistic Congress their forebears in the church in Ireland knew how to strive for holiness and constancy in their personal lives, and how to preach the joy that comes from the Gospel.
"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," said Pope Benedict in an eight-minute recorded message to the crowd, which included Taoiseach Enda Kenny and Irish President Michael D Higgins.
"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.
"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? It remains a mystery. Yet evidently, their Christianity was no longer nourished by joyful encounter with Jesus Christ: it had become merely a matter of habit."
Thousands of pilgrims from around the world have attended the week-long Congress, which has been dubbed the "spiritual Olympics" of the Catholic Church. The last time the event was held in Ireland was in 1932 when the Catholic Church held a firm grasp over the Irish people and close to a million people packed the Phoenix Park for the final public mass.
But in recent years the Catholic Church in Ireland has been rocked by several State inquiries which revealed decades of abuse and cover-ups by church hierarchy and State authorities. Cardinal Sean Brady, head of the church in Ireland, has also dismissed several calls for his resignation over his role in a secret inquiry into a dangerous paedophile priest in 1975.
Pope Benedict's address was the first time he spoke directly to Catholics in Ireland since he penned an open letter to mass-goers in 2010 in which he apologised to victims of abuse.
Despite the huge drop in support for the church, up to 20,000 people a day visited the RDS, which was transformed into a eucharistic village for the eight-day festival of faith and culture. It featured 223 keynote speakers and 160 workshops including talks, addresses, group reflections, meetings, concerts and plays.