At Bloomberg, Jeffrey Goldberg listed the three potential terror attacks he worries about the most:
1. Jewish extremists attacking the Dome of the Rock
2. "An assault by a white, Christian extremist agitated by the imagined specter of worldwide Muslim domination, either against a government target, in the Oklahoma City and Oslo manner, or against a Muslim target [in America.]
3. Another attack by Lashkar-e-Taiba of Pakistan against Mumbai.
Why these three?
In the first case "the Muslim world would ignite." In the second, an attack "would do irreparable harm to America’s image as a diverse and welcoming refuge, and could trigger the clash of civilizations extremists (both anti-Muslim Americans and anti-American Muslims) so desperately seek." And in the third, well, there is a potential for nuclear war since India would have a hard time not retaliating against Pakistan.
Goldberg is not worried about the effects of the attacks themselves - a few hundred people killed - but of the larger repercussions that could result.
Going through his list, I can understand being frightened of a nuclear war. I don't think there is any question that an Islamic attack on India is a valid concern.
As far as the Temple Mount goes, I think that the threat of the Muslim world "igniting" is overstated - it has been a threat hanging over the heads of Westerners for a long time, and one that the Muslim world is happy to use to intimidate the West to do its bidding. I call it "The Diplomacy of Fear" and there are countless examples of its use, old and recent. This is not to say that the repercussions of such an attack wouldn't be unpleasant - imagine the Mohammed cartoon riots multiplied by a hundred - but I can't see the Muslim world being much more upset at Israel than they already are.
But the fear of a Christian US terrorist is, simply, absurd. If you are going to worry about a lone terrorist, there are a lot of scenarios that are more frightening than "doing harm to America's image" - especially when Americans would be the victims! In fact, an al-Qaeda style attack in Chicago would be far more likely to turn Americans against Islam and increase the "clash of civilizations" than an American Christian Islamophobe killing Americans would do. This scenario is bizarre, to say the least.
If an American would pull a Norway-type attack in Mecca, OK, that might be something to fear. We could worry about Iran developing a nuke that they would ship to Hezbollah or Hamas. We could worry about a dirty nuke placed in Chicago's water supply. We could worry about a massive sarin attack against New York subway lines. We could worry about a Stuxnet-type attack against the electrical grid that could amplify the Northeast blackout of 2003. History shows that an assassination of a national leader can often change the course of history more than any conventional terror attack against civilians.
There is an interesting subtext to this article: that only liberal Westerners can be expected to act peacefully.
Conservative Westerners ("anti-Muslim Americans"), according to Goldberg, would jump on the side of an American anti-Muslim terrorist - a really bizarre and almost slanderous thought. Who has supported Breivik's actions?
Goldberg goes on to note that Indians and Muslims would react to attacks with much wider violence, despite India's forbearance after the Mumbai attacks.
So the reason that Goldberg isn't overly concerned about a Muslim attack against a Western country is because he believes that the West can be counted on not to retaliate. Obviously this doesn't include warmongering Bush, but the more enlightened current resident of the White House.
This is a good piece of information for potential Islamic terrorists to know.
UPDATE: Viktor Shikhman rips apart Goldberg's characterization of "radical" "messianic" Jewish "terrorists."