Pope Francis has called on the mafia to "stop doing evil" as he met relatives of their victims on Friday to demonstrate the Catholic Church's opposition to organised crime.
Over 1,000 people attended prayers with the pope at a church near the Vatican, where a list of 842 names of victims of mafia violence were read out, including butchered toddlers and renowned anti-mafia Judge Giovanni Falcone, blown up in his car in 1992.
The meeting was an attempt to draw a line under the Church's historic ties with dons claiming to be god-fearing Catholics.
"Men and women of the mafia ... change your way of life. Stop doing evil, convert," the pontiff said.
"There is still time to avoid ending up in hell, which is where you are going if you continue down this path," Pope Francis warned the country's mafiosi.
He told Italy's mobsters to relinquish their "blood-stained money", which "cannot be taken into paradise."
Pope Francis "wants to make it known that the gospel and the mafia, the gospel and corruption, the gospel and illegality, cannot go hand in hand," father Marcello Cozzi, deputy president of the anti-mafia Libera association, told AFP ahead of the ceremony.
Numerous priests fight against the Cosa Nostra in Sicily, the 'Ndrangheta in Calabria and the Camorra in Naples, sometimes paying for their bravery with their lives, but the Italian Church also has a darker side.
Mafia dons have historically attended mass, often receiving lavish funerals and presenting themselves as good Catholic benefactors, stepping in to serve local residents where the state has failed to help.
They also claim to live by a "code of honour".
Mr Cozzi said the murder of a three-year-old this week in mafia retaliation was the latest proof that such a code did not exist, and has never done so.
"In the list of victims' names there are at least 80 minors. A mafia which does not kill children does not exist, they have always killed children," he said.
The Church has long been marred by reports of financial corruption, with the Vatican Bank embroiled in claims of mafia money-laundering.
It was the main shareholder of the Banco Ambrosiano, which collapsed in 1982 amid accusations of mafia association.
Its chairman Roberto Calvi, dubbed "God's Banker", was found hanging from a London bridge that year in a suspected murder by mobsters.
Francis has moved fast since his election last year to clean up the Vatican's scandal-plagued finances, setting up a commission tasked with reform and inviting in external auditors.
Suspect accounts have been closed or flagged up for deeper inspection.
The dirty accounts "are an open wound", and if the Church is serious about tackling organised crime, full transparency is the first step, Mr Cozzi said.
The task has become more urgent than ever as the mafia increasingly swaps risky markets like weapon or drug smuggling for economic crimes.
"The real territory that needs controlling is a virtual one, with no borders, no tolls, no customs: the economy," he said.
Usury has also become big business in the wake of the economic crisis, with criminal groups "the only ones in possession of much-needed liquidity."
As well as casting light on its murky books, the Vatican has made efforts recently to honour those religious leaders who have stood up to the mafia.
Last year, murdered priest Giuseppe Puglisi was beatified for his tireless attempts to help young people in the Sicilian city of Palermo escape the clutches of the "Octopus", as the Cosa Nostra is nicknamed.
The pontiff has also made a point of speaking out loudly against human trafficking, "one of the mafia's big businesses", Mr Cozzi said.
Francis's determination to root out corruption has sparked warnings that he himself could become a target of mafia violence for threatening their interests.
Nicola Gratteri, a respected state prosecutor in the southern Calabria region, said in November that the 'Ndrangheta was "nervous".
"Those who up to now have fed off the power and wealth coming directly from the Church are nervous, upset," he said. The pope "is dismantling the Vatican's economic centres. If the mafia bosses can trip him up, they won't hesitate."
The Vatican took the warning in its stride, insisting there was "no reason for concern".