The most senior Catholic to be charged with concealing child sexual abuse — Adelaide's Archbishop Philip Wilson — has been found guilty by a New South Wales court, in a landmark ruling.

Key points: Wilson concealed child sexual abuse by a fellow priest in the 1970s

Wilson concealed child sexual abuse by a fellow priest in the 1970s He was assistant parish priest in East Maitland, NSW, at the time

He was assistant parish priest in East Maitland, NSW, at the time He could face up to two years in jail

The 67-year-old was accused of covering up abuse by priest Jim Fletcher in the NSW Hunter region in the 1970s.

During his trial, the archbishop said no one had ever come forward to tell him of allegations of child sex abuse during his 40 years as a clergyman.

However, Magistrate Robert Stone cast that claim aside in a ruling that could have ramifications in courts around the country.

Speaking outside court, abuse survivor Peter Gogarty said the verdict was "one of the most significant days in criminal law in Australian history".

"I think this will now open the doors for other jurisdictions to start looking at trying to prosecute people who deliberately looked after their institution and, literally, threw children to the wolves," Mr Gogarty said.

"On behalf of all of the victims — who have been abused in this country and elsewhere — I just want to say what an enormous relief it is that the people who let this happen are finally being brought to account."

There were gasps from those in the packed courtroom when Magistrate Stone handed down the verdict.

People were crying and shaking hands after the hearing.

Abuse survivor Peter Gogarty thanked police and the prosecution for their work on the case. ( ABC News: Brooke Wylie )

Victims want jail sentence

The prosecution has requested a custodial sentence for Wilson, for reasons of "deterrence" and "denunciation".

Wilson remains on bail on the condition that he attends his sentencing hearing, which will be held on June 19.

The harshest sentence Magistrate Stone is able to give is two years in prison, and he has the option of suspending the sentence.

"Archbishop Wilson knew what James Patrick Fletcher was up to in 1976," Mr Gogarty said.

"Fletcher was already abusing me by then, but Wilson could've stopped it, he could've got me help.

"I am very pleased that the prosecution is going to push for a custodial sentence.

"We're talking about children being sexually abused and the Archbishop knew — that to me demands a custodial sentence."

Magistrate finds witness was truthful and reliable

In a statement, Archbishop Wilson said he was "obviously disappointed at the decision published today".

"I will now have to consider the reasons and consult closely with my lawyers to determine the next steps," Wilson said.

Wilson's legal team made four attempts to have the case thrown out, arguing it was not in the public interest and that his diagnosis of Alzheimer's should preclude him from trial — although it did not preclude him from retaining his position in the church.

His lawyers maintained throughout the trial in Newcastle Local Court that while one victim, Peter Creigh, was abused by Fletcher as a child, Wilson, who was an assistant parish priest in East Maitland at the time, did not know about it.

Mr Creigh previously asked for a non-publication order on his name to be lifted.

He clutched his partner's hand as Magistrate Stone read out the verdict.

The magistrate said he found Mr Creigh to be a truthful and reliable witness.

"I am satisfied and find that Mr Creigh described to the accused he performed fellatio of Fletcher and masturbated Mr Fletcher," Magistrate Stone said.

Magistrate Stone said Wilson was trying to protect the church's reputation by concealing the abuse of Peter Creigh (centre). ( ABC News: Brooke Wylie )

Wilson 'wanted to protect church's reputation'

Magistrate Stone said he did not accept Wilson could not remember a 1976 conversation, in which Mr Creigh, who would have been aged 15 at that time, described his abuse at the hands of Fletcher.

The magistrate said Mr Creigh "had no motive or interest to deceive or make up the conversation".

Magistrate Stone said Wilson knew "what he was hearing was a credible allegation and the accused wanted to protect the church and its reputation".

The magistrate said if Wilson had reported what he knew to police, it would have helped in prosecuting Fletcher.

He said Wilson knew the Creigh family.

"He knew what the young man was telling him was believable," Magistrate Stone said.

Magistrate Stone said he accepted Wilson had no role in the assaults and that Fletcher had never made admissions to him.

Parishioners divided

Catholic parishioners attending mass at the St Francis Xavier Cathedral in the Archbishop's Adelaide diocese were divided over the court's decision.

"I think it's a very sad state of affairs for everybody because I think people are forgetting that in the '70s we were not looking for this type of situation, we didn't know about paedophiles," one person said.

"I don't think he was actually covering up, I think he was just naive to the situation and the whole thing is unfortunate circumstances."

"If he has committed crimes against society, people, kids, he needs to pay for it," said another.

"If he's guilty, then he's not representing the faith of the church… that is not what we really want to promote."