The Archbishop of Dublin said Thursday that an upcoming report on child sexual abuse involving Catholic priests will likely reveal that thousands of youngsters were abused from 1975 to 2004.

The report "will shock us all," said Diarmuid Martin, during Mass at Dublin's Pro-Cathedral.

The archbishop said the report, compiled by the Dublin Archdiocese Commission of Investigation, is expected to show that "thousands of children or young people across Ireland were abused by priests in the period under investigation and the horror of that abuse was not recognized for what it is."

The government-appointed commission was set up to investigate abuses within the Dublin archdiocese in 2006, the same year the diocese admitted that up to 102 of its priests were suspected of abusing children. The report is studying how complaints of child sexual abuse were handled.

The commission has also now begun an investigation into the Diocese of Cloyne, in County Cork. Commission member Ita Mangan said that could potentially delay the publication of the Dublin report which had been planned for this summer.

"The commission will be finishing the report in May; we then send it to the government, and they then decide when to publish it," Mangan said Thursday. "The government is obliged to publish it, but not necessarily the next day. It could be further complicated by the fact that we're also inquiring into the Cloyne diocese. It is possible the government would decide to publish the two reports together, which could then be September, October."

The Department of Justice, Equality and Law Reform said Thursday that it could not confirm any planned date of publication.

Ireland, a predominantly Catholic country, has been rapidly secularizing in recent years, spurred by the outrage at the hidden abuses within the clergy. Archbishop Martin, a Vatican diplomat assigned in 2003 to address the problem, appeared to address that disillusionment Thursday in his homily.

"There is a dramatic and growing rift between the church and our younger generations and the blame does not lie principally with young people," he said.