Within our lifetimes, this may well be a "crazy guy in a garage" project.

And the memeset I'd personally put my money on being the proximal cause is "humans are a blight upon Mother Gaia and should be removed at all costs". We don't have to imagine the existence of people who would push the Kill All Humans button if given a chance... we need merely read the right bits of the Internet. Sure, most of them would at least think twice... but there's enough that wouldn't.

I don't know if this is either a cynical or optimistic idea, but I don't know if those groups truly believe that throughout the ranks. That is why you often hear about payments to the family of suicide bombers. They aren't simply doing it for their religious beliefs, but also to help out their family. The same family that would have a 50% chance of death if the particular example virus from the article was released.

Or another way to put it, why is the pope-mobile bulletproof?

Almost all of them committing these atrocities for religious reasons. The Chinese government has treated Tibetan Buddhists horribly for decades, but you don't see any Tibetan Buddhist suicide bombers. There have been some sects of Buddhism in the past that have done horrible things, but in general it's harder to become a Buddhist suicide bomber than it is to become a Muslim suicide bomber. Some religions condemn violence of any kind. For example, I doubt anyone could be a Jainist suicide bomber.

If you don't believe me, hear it from the horse's mouth. Here is a video from a Muslim peace conference in Norway: http://www.youtube.com/watch?v=bV710c1dgpU#t=45s It will take five minutes of your time, but I think it shows best how sincere these people are.