A Catholic priest repeatedly raped and abused victims in south Australia, a royal commission into responses to abuse heard.

Peter Searson, formerly parish priest at Holy Family church in Doveton, Victoria, abused parishioners and altar boys to such an extent where one victim told the commission he sits at home in the dark with the door locked because it is the only place he feels safe, the Guardian reports.

The abuse on that victim, who identified as BVD, began in 1978 when he was nine years old while he served as an altar boy.

"He was a very scary man and and very intimidating, with a gaze that would just pierce you like he was looking right through you," BVD told the royal commission into institutional responses into child sexual abuse in Melbourne on Tuesday.

"I was very submissive as a child and I was very scared of Searson."

BVD said the priest's abuse developed from rubbing genitals to raping him.

"That happened nearly every Saturday for six months," BVD said, breaking down into tears. "Searson threatened me, telling me I would go to hell if I told anyone. I was terrified. The only person I was more scared of than Searson was my mother. There was no way I could tell her what was happening."

The royal commission was launched into institutional responses to child sexual abuse and was told by a colleague of Searson he was a "psychiatrically disturbed man."

Another victim, now aged 40, said she was abused by a family member between the ages of five and eight and then by Searson when she was in year three.

Julie Stewart gave evidence to the commission, saying she was forced to sit on Searson's lap during confession, not on the other side of the confessional barrier. This developed to him touching her genitals.

"I understood that what he was doing was sexual and it was wrong," Stewart told the commission. "I would wear tracksuit pants or stockings to make it harder for him to touch me."

"He pushed me hard against him. It hurt. He whispered; 'You are a good girl. The Lord forgives you'. I snapped. I ran out of the confessional ... sobbing and hyperventilating. I was making a lot of noise."

The commission will examine how the institution of the local Catholic church handled the case. It has also covered other institutional responses to abuse including one case involving the father of Hillsong, Brian Houston. Houston's father allegedly abused one victim in the 1970s before Hillsong was founded.

The hearing continues.