If we can laugh at ourselves and others we gain some perspective, and absolutist cultures have no place for perspective - we have a true enemy in humorlessness.

UPDATE
Though he doesn't explicitly mention humor, in today's WSJ James Q. Wilson offers a clear, concise and thorough history of separation of church and state and its centrality to modern government. He also goes into detail on the cultural histories of the West and Islam, and where they stand vis-a-vis each other:

The wall between church and state, as Jefferson called it in a letter he wrote many years later, turned out to be controversial and porous, as Philip Hamburger's masterful new book, "The Separation of Church and State," shows. But it did guarantee that in time American politics would largely become a secular matter. And that is the essence of the issue. Politics made it necessary to establish free consciences in America, just as it had in England. This profound change in the relationship between governance and spirituality was greatly helped by John Locke's writings in England and James Madison's in America, but I suspect it would have occurred if neither of these men had ever lived.

There is no similar story to be told in the Middle Eastern parts of the Muslim world. With the exception of Turkey (and, for a while, Lebanon), every country there has been ruled either by a radical Islamic sect (as with the Taliban in Afghanistan and the mullahs in Iran) or by an autocrat who uses military power to enforce his authority in a nation that could not separate religion and politics or by a traditional tribal chieftain, for whom the distinction between church and state was meaningless. And the failure to make a theocracy work is evident in the vast popular resistance to the Taliban and the Iranian mullahs.

....many traditional Islamic scholars insist that only the sharia can govern men, even though it is impossible to manage a modern economy and sustain scientific development on the basis of principles set down in the seventh century. Bernard Lewis tells the story of a Muslim, Mirza Abu Talib, who traveled to England in the late 18th century. When he visited the House of Commons, he was astonished to discover that it debated and promulgated laws and set the penalties for criminals. He wrote back to his Muslim brethren that the English, not having accepted the divine law, had to make their own.

....Both the West and Islam face major challenges that emerge from their ruling principles. When the West reconciled religion and freedom, it did so by making the individual the focus of society, and the price it has paid has been individualism run rampant, in the form of weak marriages, high rates of crime, and alienated personalities. When Islam kept religion at the expense of freedom, it did so by making the individual subordinate to society, and the price it has paid has been autocratic governments, religious intolerance and little personal freedom.