Emeritus Pope Benedict XVI has emerged from his self-imposed silence inside the Vatican walls to publish a lengthy letter to one of Italy's best-known atheists. In it, he denies having covered up for sexually abusive priests and discusses everything from evolution to the figure of Jesus Christ. Excerpts of the letter were published on Tuesday by La Repubblica , the same newspaper which just two weeks ago published a similar letter from Pope Francis to its own atheist publisher. Benedict wrote the letter to Piergiorgio Odifreddi, an Italian atheist and mathematician who in 2011 wrote a book Dear Pope, I'm Writing to You . The book was Odifreddi's reaction to Benedict's Introduction to Christianity , perhaps his best-known work. In his book, Odifreddi posed a series of polemical arguments about the Catholic faith, including the church's sex abuse scandal. The former Cardinal Joseph Ratzinger headed the Vatican office responsible for abuse cases, and was pope when scandal erupted in 2010, with thousands of people coming forward in Europe, Latin America and beyond saying they had been molested by priests while the Vatican turned a blind eye. In his letter, Benedict denies personal responsibility, saying: "I never tried to cover these things up." "That the power of evil penetrated so far into the interior world of the faith is a suffering that we must bear, but at the same time we must do everything to prevent it from repeating," he wrote, according to Repubblica . In Benedict's letter, he takes Odifreddi to task for what he said was the "aggressiveness" of his book, and responds to many of the arguments raised with piqued criticism himself. "What you say about the figure of Jesus isn't worthy of your scientific standing," wrote Benedict in his reply. He similarly criticises Odifreddi's "religion of mathematics" as "empty" since it doesn't even consider three fundamental themes for humanity: freedom, love and evil. Odifreddi said he was stunned to have received the letter. He said he sought and obtained Benedict's permission to publish the letter.