Pope Francis has said he hopes every remaining obstacle to Northern Ireland's peace process will be overcome.
He addressed an audience at Dublin Castle which included political figures from Northern Ireland as well as Secretary of State Karen Bradley, and Good Friday Agreement peace deal architect George Mitchell.
Northern Ireland's powersharing administration at Stormont has been suspended for months in a row over identity issues such as the Irish language, 20 years after a landmark accord largely ended violence.
The Pontiff said the Irish Government, alongside leaders in Northern Ireland and Britain, had created a "dynamic" context for the peaceful settlement through the Agreement of a conflict which had caused "untold pain" on both sides.
He added: "We can give thanks for the two decades of peace that followed this historic agreement, while expressing firm hope that the peace process will overcome every remaining obstacle and help give birth to a future of harmony, reconciliation and mutual trust."
Ms Bradley said the Pope was very serious and humble on the subject.
"It was good to hear him saying what he said and confronting it so openly," she said.
As he left the hall, the Pope embraced a woman with a child, minutes after he addressed the issue of clerical child abuse.
Read more: Pope Francis in Ireland
He said: "The failure of ecclesiastical authorities - bishops, religious superiors, priests and others - adequately to address these repellent crimes has rightly given rise to outrage and remains a source of pain and shame for the Catholic community. I myself share those sentiments."
He said his predecessor Pope Benedict's frank and decisive intervention incentivised efforts of the Church's leadership to remedy past mistakes and adopt stringent norms meant to ensure that they do not happen again.
He added: "It is my hope that the gravity of the abuse scandals, which have cast light on the failings of many, will serve to emphasise the importance of the protection of minors and vulnerable adults on the part of society as a whole."
Other prominent critics of the church's teaching on social issues were present in the invited audience at Dublin Castle.
They included former Irish president Mary McAleese, an opponent of the church's stance on LGBT issues.
Several bishops sat in the front row at St Patrick's Hall, including Archbishop of Armagh and primate of All Ireland Eamon Martin, and his predecessor Sean Brady.
Mr Brady said: "In the past we were not where we should have been and we have put in place measures which need to be implemented of course and followed through."
Colm O'Gorman, who was a victim of sex abuse and leads Amnesty International in the Republic, said the Pope's address was a "missed opportunity".