"All of us -- every single person has difficulty coming to understand what this really is and how prevalent it is in our societies across the world," said Oliver, whose position includes monitoring and investigating cases of priests accused of sex abuse.
When one first hears of a case of abuse, he said, "every single one of us begins with denial," which is why the entire church, at all levels, must make a concerted effort to educate its members about the reality of abuse and the best practices for protecting children.
Speaking Tuesday at Rome's Pontifical Gregorian University, Oliver said the conference the university and several Vatican offices sponsored last year for bishops and for superiors of religious orders was an important step forward, as is the pilot project for an online prevention and child protection course being run by the Gregorian-based Center for Child Protection.
Oliver spoke at the university as the center presented a report on its activities over the past year.
Responding to a reporter's question about the role of the media, especially in the United States, in forcing the church to come to terms with the reality and breadth of the sex abuse scandal, Oliver said, "those who continued to put before us that we needed to confront this problem did a service" and continually reminded the church that it had to deal with the scandal "with honesty and transparency."
Still, he said, in some parts of the world bishops and other Catholics are just starting to become aware of the problem and their need to enact measures to protect children and deal with allegations.
In 2011, the doctrinal congregation asked every bishops' conference in the world to submit guidelines for assisting victims; protecting children; selecting and training priests and religious; dealing with accused priests; and collaborating with local authorities.
Oliver said "three-quarters" of the world's 112 bishops' conferences have sent in guidelines, and the doctrinal congregation has just begun responding with observations and suggestions. Most of the countries that have not yet responded are in Africa, he said.
He also told reporters that the greatest number of cases of suspected abuse reported to the doctrinal congregation in a single year was about 800 cases reported in 2004; in the last three years, he said, the number has remained steady at about 600 "from the whole world," with most of the abuse having taken place between 1965 and 1985.
Jesuit Fr. Hans Zollner, president of the directors' committee of the Child Protection Center, said that in responding to the scandal and preventing abuse, "the road will be long and difficult because of resistance, conflicts and tensions" as well as "inertia, discouragement on the inside and attacks from the outside."
Just in the past month, he said, the church's handling of abuse cases has continued to make the news, demonstrating that "unfortunately, the matter will be with us for a long time. The church is working much more than people know, but is also the object of criticism because of its errors, its failures and the sins of the past. This is why it is extremely important to continue the work of prevention with every available means."
While some people believe the problem of child sexual abuse afflicts society at large and others "doubt the sincerity of any commitment made by the church," he said, "that which gives us energy and inspiration are the words of Jesus himself, who taught us that the truth will make us free and who tells us that his love for children is absolute and unconditional."