The Jehovah's Witnesses Church in Australia failed to report more than 1,000 alleged child sex abusers to the police, an inquiry has heard.
Instead, the commission says, the Church itself handled all the cases - some of which date to the 1950s.
One elder told the hearing that notes relating to abuse claims were destroyed so they would not be discovered.
Australia began a national inquiry into child sexual abuse in 2013, after claims of abuse in the Catholic Church.
Members of the Royal Commission into Institutional Responses to Child Sexual Abuse, whose remit includes religious groups, NGOs and state-care providers, say more than 4,000 victims have come forward.
The commission has heard allegations of abuse taking place within the Catholic Church and the Orthodox Jewish community, as well as schools and children's homes.
Angus Stewart, counsel for the commission, said that of 1,006 alleged perpetrators of child sexual abuse identified by the Jehovah's Witnesses Church, "not one was reported by the church to secular authorities".
The Church dismissed 401 members following internal abuse hearings, but more than half were later reinstated, the inquiry was told.
One Church member, identified only as BCB, gave testimony to the commission, saying that she was sexually assaulted by an elder as a teenager, and suffered depression as a result.
"The abuse changed who I was," she said. "It destroyed my confidence and my self esteem."
Another woman, given the pseudonym BCG, will give evidence that she was abused by her father, but forced by Church authorities to confront him about the allegations, Mr Stewart said.
Her father responded by blaming her for "seducing him", Mr Stewart said.
One Jehovah's Witnesses elder who handled BCB's complaint, Max Horley, admitted he destroyed notes about her allegations in case they fell into the "wrong hands".
"We do not want our wives knowing our stuff - what sort of things we are dealing with," Mr Horley told the hearing, adding that they wanted to limit the number of congregation members who knew about it.
The Church would not report cases of abuse to the police, but would encourage the victims to report it, he said, although his understanding was "a little bit unclear because I've never had to do it".