It was a question that made headlines this year, from the trial of Pussy Riot in Russia to protests in the Muslim world over a film deemed insulting to the Prophet Muhammad.
In both cases, individuals launched controversial attacks on religion that sparked harsh reactions, which created even more controversy.
In February, five members of the feminist punk-rock collective Pussy Riot staged a racy performance in Moscow's Christ the Savior Cathedral.
The unauthorized performance, which protested the Russian Orthodox Church's support of President Vladimir Putin, was called blasphemous by the church.
Punishment came swiftly. By October, two of the women were sentenced to two years in prison camps for hooliganism motivated by religious hatred while a third woman was given probation. The remaining Pussy Riot members remain in hiding.
Many human rights activists and artists in the West called the punishment worse than the crime.
A Civil, Not Criminal, Matter?
They felt the women's freedom of expression was sacrificed to protect religion, even though blasphemy itself is not a criminal offense in Russia.
According to Barbara Trionfi, press-freedom manager at the Vienna-based International Press Institute, such cases in the West are usually resolved under civil, not criminal, law:
"In the case of defamation, and in the case of insult in general, there is the use of civil laws -- that is, lawsuits -- and this is certainly a practice which is absolutely accepted," she says.
Trionfi maintains that making blasphemy or defamation punishable by prison intimidates individuals and the media into censoring themselves. And that does not just limit freedom of expression; it also protects authorities from criticism.
The other controversy was over "Innocence of Muslims," a low-budget film by a group of private individuals in the United States which depicted Islam's Prophet Muhammad as a womanizer. It, too, sparked an immediate reaction.
In September, at least 50 people died in protests across the Muslim world.
U.S. President Barack Obama told the UN General Assembly on September 25 that freedom of expression must be permitted for all, even though some abuse it.
"The strongest weapon against hateful speech is not repression," he said. "It is more speech -- the voices of tolerance that rally against bigotry and blasphemy, and lift up the values of understanding and mutual respect."
Depth Of Feeling
But Egypt's President Muhammad Morsi offered a different view. He called for "freedom of expression that is not used to incite hatred against anyone."
Geneive Abdo of the Stimson Center in Washington, D.C. suggests that the two presidents' views underline the divide between the West and the Muslim world over how much the law should protect religion.
According to Abdo, religion is paramount in Muslim countries, where the legal codes are drawn from both Shari'a and secular law:
"As a Muslim, you are forbidden from defaming the Prophet in any shape or form, so that's where we get into the difference of opinion," she says.
Abdo also maintains that Westerners who blame the unrest in the Muslim world on Islamic extremists underestimate the depth of feeling.
"The West sometimes likes to convince itself that it is only the extremists who disagree, that it's these extremist Muslims who are burning embassies who do not agree with our Western values," she says. "Well, that's not really accurate. I think the vast majority of Muslims don't agree with our Western values on this particular point, but they have different ways of [peacefully] expressing their grievances."
The film "Innocence of Muslims" is the latest chapter in a history of tensions that includes the riots over the Muhammad cartoons in 2005 and Ayatollah Ruhollah Khomeini's 1989 death fatwa for Salman Rushdie.
The coming years are almost certain to bring further disputes.
The world continues to wrestle with how freedom of speech can be balanced with freedom of religion. But so far, there is no universal answer.