Anonymous is claiming to have brought down several Vatican websites, which were offline for most of Wednesday.
But while the main Anonymous Twitter account claims the attack was carried out 'for the pure, simple lulz', the Italian branch says in a statement on its website that it has a host of good reasons, from book-burning to dodgy financial practices.
"In more recent times, you have played a significant role in helping Nazi war criminals find refuge in foreign countries and evade international justice," it says.
"Every day, you have given permission to many members of the clergy responsible for molesting children, covering things up when the facts become public domain."
The group stresses that it has nothing against Christianity, but is protesting against the Catholic Church's 'absurd and anachronistic' practices - including opposition to contraception and interference with Italian political affairs.
The timing of the hack may also reveal a possible British connection. On Sunday, the country's most senior Catholic, Cardinal Keith O'Brien, caused astonishment and outrage by describing marriage as a 'universally accepted human right' - and then adding that extending that human right to gay people was 'grotesque'.
The Vatican attack followed a similar assault on the website of Panda Security, over claims that the company had helped the FBI capture six hackers, including the high-profile Sabu.
Panda claims that the server which was compromised was used only for marketing purposes and to host blogs.
"The attack did not breach Panda Security’s internal network and neither source code, update servers nor customer data was accessed," it says.
"The only information accessed was related to marketing campaigns such as landing pages and some obsolete credentials, including supposed credentials for employees that have not been working at Panda for over five years."