William Donohue - The president of the Catholic League for Religious and Civil Rights has come under scathing criticism after he wrote that the staff of Charlie Hebdo have a "long and disgusting record" of insulting Muslims and other religious figures.

On Wednesday Jan 7, a group of armed men got into the offices of weekly French satirical paper Charlie Hebdo and opened fire, killing 12 people. The attack by Islamic extremists was apparently in retaliation for the paper's repeated controversial cartoons, which ridiculed Prophet Muhammad and other Muslim religious figures.

While many commentators have underlined the controversial nature of the Charlie Hebdo's cartoon, they have also noted that the staff of the publication were simply exercising their basic right to freedom of speech.

But according to William Donohue, Charlie Hebdo had exceeded the provisions of the freedom of speech, which gives commentators the right to 'lampoon' public figures. He said the weekly satirical paper was downright publishing vulgar material.

"Killing in response to insult, no matter how gross, must be unequivocally condemned. That is why what happened in Paris cannot be tolerated. But neither should we tolerate the kind of intolerance that provoked this violent reaction," he wrote.

Since William Donohue's op-ed on the Paris shooting was published on Wednesday, the 67 years old civil activist has been challenged by many commentators.

On Thursday, Fox News anchor Megyn Riley, who said that the staff of Charlie Hebdo were "courageous" to have continued working after receiving several terrorist threats, defended their use of cartoon to criticize of public figures.

"The political cartoon is a weapon of attack, of scorn and ridicule and satire; it is least effective when it tries to pat some politician on the back," Riley said, quoting a landmark trial in 1988.

Although both Donohue and Riley agreed that freedom of speech is the means to an end, a British radical Muslim cleric has thrown that entire concept out of the window.

According to Angem Choudary, the concept of freedom of expression is not compatible with the laws of the Qu'ran.

"Contrary to popular misconception, Islam does not mean peace but rather means submission to the command of Allah alone," he wrote in an op-ed published by USA Today. "Muslims do not believe in the concept of freedom of expression, as their speech and actions are determined by divine revelation and not based on people's desire."

Choudary went on to explain that the Qu'ran prohibits anyone from insulting prophets. According to him, in an Islamic State, such an act attracts a death penalty.

He also noted the French government was responsible for the attack as it failed to do anything to stop Charlie Hebdo's repeated ridicule of Muslim religious figures.