In video testimonies watched by summit participants, one survivor from Africa said she was forced to have sex with a priest from the age of 15.
The summit, titled "The Protection of Minors in the Church", begins in Rome today and continues until Sunday with over 100 bishops throughout the world behind closed doors.
They said the stunt was to protest the failure of the Polish Catholic Church in resolving the problem of clergy sex abuse.
Another victim, from the United States, said he still felt pain after the "total loss of the innocence of my youth" and urged bishops to show "leadership, vision and courage".
A survivor from Chile told the churchmen they had inflicted even more pain on victims by discrediting them and protecting the priests who abused them. This lasted for 13 years.
"The first thing they did", he said, "was treat me as a liar, turn their backs and tell me that I, and others, were enemies of the Church".
"I got pregnant three times and he made me have an abortion three times, quite simply because he did not want to use condoms or contraceptives", she said.
The head of the Church said this in his speech at the start of a four-day summit, which is aimed at tackling the child sexual abuse within the institution.
"You are the physicians of the soul and yet, with rare exceptions, you have been transformed - in some cases - into murderers of the soul, into murderers of the faith", the man said. "What a bad contradiction", he said. Also included in the proceedings: survivor video testimonials and an emotional speech by Philippines Cardinal Luis Tagle, who noted victims had been dismissed much as Jesus was before crucifixion.
The Maltese spent 10 years as the Vatican's top prosecutor on paedophilia cases, and was picked by Francis to travel to Chile last year to hear from victims whose voices had previously been silenced by an internal Church cover-up.
Burke and Brandmüller claim the rampant sexual abuse of children by Catholic priests and church leaders is "blamed on clericalism" but the "first and primary fault of the clergy does not rest in the abuse of power but in having gone away from the truth of the Gospel".
More than 30 years after the scandal first erupted in Ireland and Australia and 20 years after it hit the USA, bishops and Catholic officials in many parts of Europe, Latin America, Africa and Asia still either deny that clergy sex abuse exists in their regions or downplay the problem.
But the suggestion that Church laws need only fine-tuning has angered many, including Anne Barrett Doyle, the co-director of BishopAccountability.org, a public database that documents cases of proven or suspected cleric sex crimes.
"They said this was going to just be a teaching session, but he is now talking about concrete measures".
"My hope will be that people see this as a turning point", Cardinal Blase Cupich of Chicago, a member of the organizing committee, said Monday at a news conference.