McClellan singled out the Roman Catholic Church in particular for often putting reputation above the safety of children in what they found to be decades of systematic sexual abuse -- a familiar pattern of scandals dogging Catholic institutions globally.

"Some leaders felt their priority was to protect the reputation of the institutions ... alleged perpetrators often had access to children even when religious leaders knew the danger," McClellan told advocates, lawyers and members of the public who attended the final hearing.

Hundreds of Catholic priests accused

McClellan noted that there may be "resentment" from institutions that the Royal Commission was interfering in their affairs.

"But changes must be made," he said.

On Friday, the Royal Commission, the full title of which is the Royal Commission into Institutional Responses to Child Sexual Abuse, will present a final report covering its investigations to the Governor-General in Canberra.

McClellan said the report will make recommendations that aim to "support and inform" Australian governments, institutions and the general public in preventing and responding to child sexual abuse.

They are expected to include issues such as stronger working with children checks, streamlining compensation and making it easier to prosecute historical abuse.

Commission could lead to 'momentous' change

Earlier this year 85 recommendations were made ahead of the final findings in a criminal justice report issued by the commission, including the fact priests should be charged for failing to report child sexual abuse spoken of in a confession box.

Due to the "sacred seal" of the confessional there have been calls by expert witnesses during the inquiry for Pope Francis to guide Catholic leaders worldwide to encourage priests to report crimes to police and to also consider the affects of celibacy and seminary training on possible causes of child abuse.

Former Catholic priest, professor Des Cahill, who was a consultant to the Royal Commission during the inquiry, told CNN he believes the Catholic Church will be keen to see that it's implementing all the recommendations to create a professional priesthood.

"Even though it would a momentous cultural change, I think it's possible the church would drop mandatory celibacy and would take such a recommendation very seriously," he said.

"I think the final report will also focus on very much on the sense of loneliness and lack of intimacy and how that contributes to child abuse."

He added that dropping mandatory celibacy would be the biggest change in the Catholic Church for over 50 years since Mass began to be conducted in English instead of Latin.

Leonie Sheedy, the CEO of Care Leavers Australasia Network, told CNN the inquiry has served as a "world-class example" and the findings must be listened to by institutions including the Vatican.

"Survivors are no longer afraid to speak up thanks to this commission and hassle those in power to be accountable," she said, "They have started to put the blame squarely where it belongs."

Despite all the evidence in the extensive inquiry McClellan reminded the Australian public that abuse in a family setting was an even greater problem.

"It's intolerable and the responsibility of our entire community that children are being abused and to do what we can to protect them," he said.

At the end of the final hearing Gail Furness, senior counsel assisting the commission, read out some of the messages written by survivors who gave evidence in a special book which will be held at the National Library of Australia.

"For us that once had no voice now we can be heard. And for us whose lives were destroyed now we can begin to heal," one message said.