Press campaign group Reporters Without Borders marked Thursday's first anniversary of the attack on French satirical weekly Charlie Hebdo by warning against what it called "religious correctness".
The organisation cautioned against what it called "the insidious imposition of a 'religious correctness' that poses a major threat to the journalistic freedom to inform others (and make them laugh)," in a statement.
It noted the controversy sparked by the cover of Charlie Hebdo's Wednesday edition, which depicts a gun-toting God figure on the run.
The Vatican criticised the cover for failing to "acknowledge or to respect believers' faith in God, regardless of the religion."
It added: "Using God to justify hatred is a genuine blasphemy."
The fiercely secular publication's drawings of the Prophet Mohammed drew the fury of Muslims around the world and inspired the bloody attack on its offices on January 7 last year.
"Some may feel offended or hurt by criticism of their beliefs, especially in the form of satire. But freedom of information and expression... must not be constrained or limited by anyone's convictions or sensibilities, or else a form of totalitarianism will take hold before we know it," the Paris-based group, known by its French initials RSF, warned.
"RSF deplores the self-censorship and overcautiousness that has taken hold in the media in democratic countries," it said.
Concepts such as blasphemy -- which is penalised in 94 countries, RSF said -- are used to create an exception to freedom of expression "for which there is absolutely no provision under international law," it said.
RSF noted that two Turkish journalists still face charges for reprinting some cartoons published by Charlie Hebdo after the massacre, while Saudi blogger Raif Badawi was sentenced to 10 years in prison and 1,000 lashes for "insulting Islam".