Catholic Primate of Ireland Archbishop Eamon Martin has said the findings at the site of the Tuam mother and baby home "allows us to peer into the past" and it is a past that many in the church are ashamed of.
Dr Martin said we need "to open it up carefully and respectfully" and establish the truth.
He said he hopes by looking on the past it will help to evaluate and critique the present, mentioning the treatment of migrants at direct provision centres as one area where improvement is needed.
Dr Martin said the Tuam site is opening up a chapter in the life of society where there was a terrible stigma against unmarried mothers.
He said the church ostracised, stigmatised and isolated unwed mothers.
Tuam showed the level of care and support offered had disproportionate levels of malnutrition, poverty and infant mortality, he said.
He said only the truth would help people move on and understand the terrible dark chapters of the past.
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Dr Martin, the Archbishop of Armagh, also meanwhile urged politicians in Stormont to agree a way forward after the recent elections "for the common good".
He said moving forward is difficult and painful and can mean sacrifice and compromise.
Dr Martin said people went out and voted in large numbers to invest trust in people to go about the business of politics, rather than brinkmanship or blame calling.
He said politics is about give and take and we need politicians to get on top of important issues like Brexit , health education, infrastructure, family and welfare.