In an ideal world, Muslims who interpret the Koran to justify violence would convert to Catholicism, and artists who think they have an absolute right to insult people of faith would follow suit. If both did, we would have peace and civility.
Catholicism teaches that it is immoral to intentionally kill innocent persons, beginning with life in the womb. It is not a pacifistic religion—it believes in just wars—though it naturally inclines towards non-violence. It most certainly does not counsel violence as a right remedy to insolent behavior. Muslims who say it is morally justified to kill obscene artists, citing the Koran as their impetus, would do us all a favor if they converted to Catholicism.
Catholicism teaches that freedom is the right to do what you ought to do. As such, it is always tied to duty, and to individual responsibility. Once that understanding breaks down—as it has in the West—trouble follows. Unfortunately, many artists interpret their rights as a solo exercise, disconnected from duty or responsibility. But autonomy can never be a sturdy guide to morality: it devolves into relativism and to a wholesale disrespect for the rights of others. Narcissistic artists who associate obscenity with creativity would do us all a favor if they converted to Catholicism.
The central problem with Muslim extremists and irresponsible artists is that neither embodies the virtue of restraint. If they did, they would not act as the barbarians and libertines that they are. Catholicism is the answer.