Archbishop Anthony Fisher on Friday told the Royal Commission into Institutional Responses to Child Sexual he didn't think he could make it a condition of absolution that a person incriminate themselves.

But he told the inquiry he would strongly encourage them to get psychiatric help and hand themselves in.

"If they are genuinely contrite by every sign that I can see then I'll forgive their sin as I would a terrorist, a murderer, many other very grave matters," he said on Friday.

Five of Australia's Catholic archbishops fronted the Royal Commission into Institutional Responses to Child Sexual Abuse in Sydney on Friday, for the last day of the final hearing into the Australian Catholic Church. 

The other archbishops said they would be willing to withhold absolution from a confessed child sex abuser.

Senior leaders told the commission they believed mandatory celibacy was a contributing factor, but not the cause of abuse child sexual abuse. Earlier this week, Archbishop Fisher said the response by church leaders to child sexual abuse allegations amounted to “criminal negligence".

"I think you might want to use stronger words (than failure) in some cases, that it was a kind of criminal negligence to deal with some of the problems that were staring us in the face," he told the inquiry on Thursday.

"In other cases, I think there were people that were just like rabbits in the headlights, they just had no idea what to do, and their performance was appalling.”

Earlier this week, Archbishop of Perth Timothy Costelloe told the inquiry there had been a “catastrophic failure in leadership” in regards to sexual child abuse.

"If they are genuinely contrite by every sign that I can see then I'll forgive their sin as I would a terrorist, a murderer, many other very grave matters," he said in Sydney on Friday.

Archbishop of Brisbane Mark Coleridge said structures within the church had also failed.

“Structures are only as good as the people you put in them, and I'm afraid many of the structures did struggle, and even fail, because the people who were in those structures seemed unable to do what the structure itself require,” he said

The inquiry also heard the Christian Brothers Catholic order will disappear from Australia in the coming decades.

Oceania provincial leader Peter Clinch said the country's youngest Christian brother is in his 50s and the order no longer seeks applicants for its novitiate.

The Christian Brothers, despite declining membership, spent $1.5 million defending convicted abuser Brother Robert Best. On Wednesday the commission heard the order was forced to fork out $14 million to top up payments to 165 victims.