Mandatory celibacy “remains the major precipitating risk factor for child sexual abuse”, Dr Peter Wilkinson and Professor Des Cahill of RMIT University’s Centre for Global Research found after a five-year study into systemic reasons for child sexual abuse within the Catholic Church.

Catholic children, and particularly boys, remained at risk from “psychosexually immature, sexually deprived and deeply frustrated priests and religious brothers”, and the “deeply homophobic environment” within the church and its seminaries “contributes to psychosexual immaturity”, the report released on Wednesday found.

An assessment of 26 key Catholic child sexual abuse studies around the world, including the NSW Special Commission of Inquiry into Maitland-Newcastle diocese, a Victorian parliamentary inquiry and the Royal Commission into Institutional Responses to Child Sexual Abuse, shows about one in 15 priests commit offences against children.

Rates differ across dioceses and among religious congregations. The risk of offending is much higher among religious brothers with little contact with women, who were educated at male-only schools, appointed to male-only schools and living in all-male communities, the report found.

“The lack of the feminine and the denigration of women within church structures is one key, underlying risk factor in the abuse,” Dr Wilkinson and Professor Cahill said.

A decision by Pope Pius X in 1910 to lower the confessional age to seven indirectly put more children at risk of abuse, and popes and bishops created a “culture of secrecy” which led to “gross failures in transparency, accountability, openness and trust”, they found.

The study explored how Catholic organisational policies, practices, processes and attitudes predisposed, influenced and facilitiated individuals to commit sexual and physical abuse against children.

It also explored how the church’s theological frameworks, organisational structures, governance processes and culture contributed to the abuse and church leaders’ inadequate responses.

It included an assessment of the NSW Special Commission of Inquiry in 2013 into offending by priests Denis McAlinden and Jim Fletcher in the Maitland-Newcastle diocese over decades, and the responses of former bishops Leo Clarke and Michael Malone.

The report concluded McAlinden, an Irish Redemptorist priest sent to Australia in 1949 at the age of 26, was one of the country’s “most prolific paedophile priests”, whose transfer from Ireland was because his religious leader “wanted McAlinden out of Ireland, and far-away Australia seemed a good bet”.

Professor Cahill and Dr Wilkinson said the NSW Special Commission of Inquiry, headed by Margaret Cunneen, SC, had “undoubted achievements”, but it was unfortunate that it did not examine all cases of priest offending in the Diocese of Maitland–Newcastle in the post-World War II period.

“It is also unfortunate that, because of its technical and narrow legal focus, it did not examine the personal, family and seminary circumstances of either offender, or the structural and systemic factors that permitted McAlinden and Fletcher to offend for so long without being held accountable,” they found.

The groundbreaking report, Child Sexual Abuse in the Catholic Church: An Interpretive Review of the Literature and Public Inquiry, is believed to be the first informed by researchers with significant theological training and knowledge of church practices. Both men trained as Catholic priests and later left the priesthood.

Professor Cahill is Professor Emeritus of intercultural studies in the school of global, urban and social studies at RMIT University in Melbourne. Dr Wilkinson is a founding member of the Melbourne-based Catholics for Renewal group.

“Peter Wilkinson and I set out to try to answer the question: Why has the Catholic Church and its priests and religious brothers, more than any other religious denomination, become synonymous with the sexual mistreatment of children?” Professor Cahill said.

“From any perspective, whether in size, complexity or historical legacy, the Roman Catholic Church is an awesome entity. One may not like the Catholic Church, but no one can ignore it.”

While the global Catholic Church child sexual abuse issue had been described as a crisis, scandal, nightmare or scourge, “the sexual and emotional abuse of children within Catholic settings by priests, religious brothers and sisters, is ultimately a tragedy of immense proportions”, he said.

The report found that by 2015 the number of baptised Catholics in the world was 1.285 billion people, or 17.7 per cent of the world population.

Growth in the church was particularly strong in Africa, while in Asia and the Americas growth was in proportion to the population growth in each continent.

Between 1975 and 2015 the number of priests worldwide increased by just 2.7 per cent. The number of religious sisters and brothers declined significantly, with a 30 per cent drop in the number of sisters, and a 21 per cent drop in the number of brothers.

In 2014 6263 priests were ordained, 4484 priests died and 716 “defected”, or resigned.

There were 136,572 church mission stations around the globe without a resident priest, the report found.