He also said such abuse was no more prevalent than elsewhere.
"I never tried to cover up these things," the former Cardinal Joseph Ratzinger said in a letter to a prominent Italian atheist and math professor that was excerpted in Italian newspaper La Repubblica with Benedict's permission.
"That the power of evil penetrates to such a point in the interior world of the faith is, for us, a source of suffering," said Benedict, who had headed the Vatican office responsible for investigating all abuse before his election as pope in 2005.
He was also the first pope to meet with abuse victims.
"On the one hand we must accept that suffering, and on the other, at the same time, we must do everything possible so that such cases aren't repeated," he told Piergiorgio Odifreddi in the Aug. 31 letter.
He also denied a claim that abuse is pervasive in the Catholic Church.
"It's also not a motive for comfort to know that, according to sociological research, the percentage of priests guilty of these crimes is no higher than in other comparable professional categories," he said.
"In any event, one must not stubbornly present this deviance as if it were a nastiness specific to Catholicism," Benedict said in his letter.
His comments -- the first released publicly since he left office Feb. 28 -- appear to be the first in which Benedict publicly rejected personal responsibility for covering up the abuse by pedophile priests, the BBC said.
Benedict said when he abdicated he intended to retreat to a life of prayer.
His comments were a response to points made in Odifreddi's 2011 book "Dear Pope, I'm Writing to You," which in turn was a response to Benedict's 2004 book "Introduction to Christianity."
Odifreddi's book posed a series of provocative arguments about the sexual abuse scandals gripping the church, the Religion News Service said.
In a short essay accompanying the letter's excerpts, Odifreddi says he was "stunned" to receive a reply from the retired pontiff.
He said he wrote his book because he believed Benedict's ideas were "sufficiently firm and strong to be able easily to withstand a frontal assault."
He said he would include the entire letter in a new edition of his book.
Jeff Anderson, a Minnesota attorney who has handled abuse lawsuits against the church, told the Religion News Service he considered Benedict's letter "alarming and disturbing."
The Survivors Network of those Abused by Priests issued a statement saying: "The opposite of 'covering up' is 'uncovering' or 'disclosing,' We cannot name one predatory bishop, priest, nun, brother or seminarian who was publicly exposed because of Benedict."