From BBC News Northern Ireland
Monsignor Eamon Martin has been appointed as coadjutor (assistant) Archbishop of Armagh. It was announced by the current leader, Cardinal Sean Brady on Friday.
Msgr Martin said the church must learn from the "terrible trauma" of abuse.
Former Bishop of Derry Edward Daly said he was seen as "a clean pair of hands" after the church's abuse scandals.
"He does not carry any baggage from the past with him," the retired bishop said.
"It's a challenging time for the church in Ireland. He has been asked to lead that church".
Msgr Martin said the church had to learn from past scandals.
"I think today of all those who have been abused by clergy, and the hurt and betrayal they have experienced," he said.
"As the words on the Healing Stone at the International Eucharistic Congress remind us - they have been left with a lifelong suffering.
"I am saddened that many good Catholics were let down so badly over the issue of abuse and that some have even stopped practising their faith.
"As a church, we must continue in our efforts to bring healing to victims and ensure that young people are always protected, respected and nurtured."
Cardinal Brady has been under pressure to resign over revelations about his handling of clerical abuse claims.
It followed a BBC documentary last year that found that when he was a priest, he had names and addresses of those being abused by paedophile priest Brendan Smyth, but did not pass them to police or parents.
But he has consistently resisted resignation calls.
Cardinal Brady, 73, announced changes to the hierarchy at Mass in Armagh on Friday.
"I am delighted that the man chosen is Monsignor Eamon Martin," he said.
"I congratulate you most heartily, Monsignor Martin. I welcome you to the city and the Diocese of Patrick."
Earlier, the Irish Catholic newspaper described the appointment as an "exit strategy" for Cardinal Brady.
The paper's editor, Michael Kelly, told the BBC the identity of the coadjutor bishop had been a well-guarded secret.
"This is an exit strategy for Cardinal Brady and probably something where this new shadow bishop will take over within the next three or four months," he said.
"It's been very clear that the cardinal's position has been, to say the least, difficult in the church and the Vatican has been engaged in a search for his successor.
"It seems now they have eventually found a successor who will shadow the cardinal, allowing the cardinal, at least on paper, or at least publicly, to go at a time of his own choosing."
Meanwhile, the Church of Ireland's Bishop of Derry And Raphoe, Ken Good, congratulated Msgr Martin on his appointment.
He said he had enjoyed working with him over the past few years and described him as "a man of spiritual depth, of humility and of vision".
"I will be sorry to see Monsignor Martin move away from his native city, and will miss his friendship," he said.