A NSW parliamentary inquiry on Monday was told of the disturbing allegations from two former students of western Sydney's Redeemer Baptist School.
Edward Garth, 23, said he was shunned after "escaping" the broader Redeemer community in November.
He told the committee about a study-stay during school holidays when he slept in the same building as principal and church elder Jonathon Cannon.
"I remember one night before dinner, I was in the kitchen getting a drink," Mr Garth said.
"As I walked into the living room, which was my bedroom at the time, I saw (Mr Cannon), my principal, walk out of the bathroom into the living room naked before heading to his room.
"He was startled, and when they saw me, he ran to his room. I don't know why he didn't cover himself with a towel."
Mr Garth said he reported the incident, but it got back to Mr Cannon, the principal's brother Noel and the then-pupil's own parents, who scolded him.
Former student Emma Hughes told the inquiry the culture inside the school left much for students to "untangle" as adults.
School camps, away from parents, were especially anxiety-inducing.
On occasion, a student would have to share a bed with teachers in a caravan park or school-owned cabins to save space, she said.
Her submission stated nothing untoward happened to her during the stays.
"Usually, the student would be a community member, which in itself says they knew maybe they shouldn't be doing it," she said.
"But I recall when I was in year 6, I would share a bed with (a) teacher, and in an effort to be fair, she made it so we would rotate every night ... so that we all didn't have to."
Staff, often known by kinship titles like "uncle", regularly crossed conversational boundaries, Mr Hughes said.
"Often, personal things were discussed in very public matters," she said.
"The nature of boundaries is really something which is not particularly, I believe, understood by staff at Redeemer in the way we understand it in most school contexts."
The school also had an emphasis on surveillance and "dobbing", public humiliations and punishment, she said.
A boy and girl were made to stand on chairs in front of a year 7 class after teachers intercepted a love note, Ms Hughes said of her time at the school.
Noel Cannon read the note to a collection of students before they were "dressed-down in front of four year groups and many teachers", she said.
The parliamentary committee is investigating the management of the Parramatta-based school and oversight from government bodies.
The Communities and Justice Department received 15 risks of significant harm notifications since 2004 but they had not triggered a field assessment, an earlier response to questions on notice revealed.
Mr Cannon and other school representatives were invited to appear at the inquiry and state the school's case.
Committee chair Abigail Boyd said she was disappointed an attempted summons to appear went begging.
AAP has contacted the school for comment on the students' allegations.