Fareed Zakaria writes in Newsweek:
What this is about, as Tony Blair has argued, is fanaticism. Radical ideologies of hate and violence have often seduced disaffected young men searching for some great cause. Forty years ago they would have embraced Leninist revolutionary dogma, with Che Guevara as the bin Laden of his day. Today, for Muslims, it is a violent interpretation of Islamic fundamentalism. Born in the Middle East, it has spread like a virus across the Muslim world and into the Islamic diaspora in the West.
The good news is that in the heart of the Muslim world, this ideology is not doing so well. The bombings, increasingly of civilians, are showing Al Qaeda and its ilk in their true light. Arabs are finally denouncing terrorism and also the ideologies that feed it. They need to do much more, and far more forcefully. It's a cliche, but true, that ultimately only Muslims can win this fight.
As always with Zakaria, the entire article is well worth reading.