(Adds more from essay, new critic)
By Philip Pullella
VATICAN CITY, April 11 (Reuters) - Former Pope Benedict has blamed the Catholic Church's sexual abuse scandal on the effects of the sexual revolution of the 1960s, homosexual cliques in seminaries and what he called a general collapse in morality.
Critics accused Benedict, who before becoming pope in 2005 was for 23 years in charge of the Vatican doctrinal office that has been widely criticised for its handling of abuse cases, of trying to shift blame away from the Church.
But in a rare essay, he also said the Church's legal system had at times been overly protective of accused clerics, citing what he called judicial guarantees that were "extended to such an extent that convictions were hardly possible".
The 91-year-old, who in 2013 became the first pope in six centuries to resign, argued that the sexual revolution had led some to believe paedophilia and pornography were acceptable. He also said an openly gay culture in some Catholic seminaries meant they had failed to train priests properly.
"It could be said that in the 20 years from 1960 to 1980, the previously normative standards regarding sexuality collapsed entirely, and a new normalcy arose that has by now been the subject of laborious attempts at disruption," Benedict wrote.
Benedict was head of the doctrinal office when the first wave of abuse cases were exposed in Boston in 2002. Later, as pope, he took action against some paedophiles that had been blocked during the reign of his predecessor, John Paul.
Abuse scandals in Ireland, Chile, Australia, France, the United States, Poland, Germany and elsewhere have forced the Church to pay out billions of dollars in damages to victims and close parishes. Many cases date back decades before the 1960s.
Revelations that predatory priests were often moved from parish to parish rather than expelled or criminally prosecuted as bishops covered up the abuse have shaken the church globally and undermined its authority.
Benedict offered his evaluations in a long essay in Klerusblatt, a monthly Church magazine in Bavaria, his native region of Germany. A Vatican official confirmed it was authentic.
The impetus for the essay, titled "The Church and the Scandal of Sexual Abuse", was a summit of senior bishops that Francis, his successor as pope, held in February to discuss the crisis, he said.
"Among the freedoms that the Revolution of 1968 sought to fight for was this all-out sexual freedom, one which no longer conceded any norms," Benedict wrote, according to an English translation published by several Catholic websites.
He said the spread of explicit sex education for young schoolchildren and nudity in advertising had contributed to a loosening of moral bearings and an "absence of God".
Some theologians took to Twitter to criticise Benedict.
"This is an embarrassing letter," said Brian Flanagan, professor of theology at Marymount University in Virginia.
"The idea that ecclesial abuse of children was a result of the 1960s, a supposed collapse of moral theology, and "conciliarity" (the Church after the 1962-65 Second Vatican Council) is an embarrassingly wrong explanation for the systemic abuse of children and its cover up."
Julie Rubio, a professor at Santa Clara University's school of theology, called Benedict's reasoning "deeply flawed", adding: "The willingness to blame a permissive culture and progressive theology for a problem that is internal and structural is stunning."
Benedict wrote that after the Second Vatican Council there was a "far reaching breakdown" of the traditional methods of priestly formation that coincided with a dissolution of the Christian concept of morality.
"In various seminaries homosexual cliques were established, which acted more or less openly and significantly changed the climate in the seminaries," he writes, adding that the situation has now improved.
Late last year, Australian Cardinal George Pell became the most senior Catholic to be convicted for child sex offences. His role as a former top adviser to Pope Francis brought the scandal to the heart of the papal administration. (Reporting By Philip Pullella; Editing by Catherine Evans)
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