The former Pope has described the work of prominent atheist Richard Dawkins as “science fiction”.
Odifreddi's 2011 book was his reaction to Benedict’s best-known tome Introduction to Christianity.
In his first public comments since he retired in February, Benedict thanks Odifreddi for his attempts to engage in an open dialogue with the Catholic faith.
The 86-year-old writes of his surprise that Oddifreddi viewed his book so worthy of such detailed discussion, given that he considers theology to be “science fiction”.
He writes: “An important function of theology is that of maintaining religion connected to reason and reason to religion. Both functions are of vital importance for humanity."
He adds: “Besides, science fiction exists in the sphere of many sciences ... Richard Dawkins’s The Selfish Gene is a classic example of science fiction.”
It’s unlikely to be any skin of Dawkins’s nose, however.
Back in 2010, he penned a column in the Washington Post and on his own website in which he described Benedict as “A leering old villain in a frock, who spent decades conspiring behind closed doors for the position he now holds.”
He went on to describe the Catholic church as a "profiteering, women-fearing, guilt-goring, truth-hating, child-raping institution."
Benedict also used his letter to deny that he tried to cover up sexual abuse of children by Roman Catholic priests.
Yet despite his insistence: “I never sought to conceal these things,” his assertions have been rejected by the Survivors Network of Those Abused by Priests (SNAP).
“In the Church’s entire history, no one knew more but did less to protect kids than Benedict,” said a SNAP statement reported by Reuters.
Benedict's letter goes on to defend the Church’s record in other areas: “If it is not right to keep silent about the evil in the Church, one should not either hide the great luminous trail of goodness and purity that the Christian faith has traced down the centuries.”