Wait, you have a hard time believing they can be so recruitment with a message based on an interpretation of an old book?

More than 2000 years of human history and religion shows that an awful lot of things (both positive and negative for the world) have come from religion, based almost entirely on old books and interpretations. The supposed word of a supposedly all knowing/powerful deity is enough inspiration for an awful lot of people.

This is simply false. Most terrorists are highly educated. The 9/11 terrorists had a college education, some had PhD's.

Being educated does not mean you're above believing in bullshit. There are a lot of highly educated people with a college education or a PhD who believe him ghosts, crop circles, bigfoot, alien abductions, the 'dangers' of GM food, conspiracy theories or think that vaccines cause autism.

That doesn't make those beliefs more plausible, regardless of if a certain amount of smart people believe in them. Similarly, it doesn't shield people from religious extremism, or any other form of extreme view for that matter. People are irrational, some lack critical thinking skills (and everyone forgets to use them at least some of time). You don't become a Vulcan the minute you get through college.

Exactly. This is not about desperate, mentally unwell, and disaffected people, but about people who sincerely think that the best thing for this world is to implement the Qur'an to the last letter. You can be a rocket scientist and a religious idiot at the same time.

Highly educated people cannot possibly be desperate, mentally unwell, or disaffected? That's also "simply false" and you say so yourself: "You can be a rocket scientist and a religious idiot at the same time". You can be highly educated and a lot of things at the same time (which one would know from reading HN on a regular basis), but perhaps only the traits that fit your narrative are allowed.

Being a religious idiot is not the same thing as being desperate, mentally unwell, and disaffected. The point is that the picture that is being sketched is in-congruent with reality. If we want to have any chance to solve this issue the first step needs to be a honest examination of the causes, not academics taking their pet topics and trying to fit terrorism and ISIS into that.

What causes a successful college student who has just gotten a job as an architect to decide that the best use of his life is to fly a plane into a building? What causes a person in their twenties in Europe to decide that the best use of their life is to go to Syria to join the Islamic State? Or to go to Paris and shoot up a theater?

Let's back up a bit. What causes a person to decide to go to planned parenthood to shoot up a bunch of doctors? Is it because of income inequality? Climate change? Russian foreign policy? Or maybe it is because he is sincerely convinced that the metaphysics of this world work as follows. At the time of conception the soul enters the embryo. In order for this soul to enter heaven the baby needs to be baptized. If this doesn't happen then their soul either goes to burn in eternal hell or to limbo. Now, there is a clinic next door where people are literally killing babies before they are baptized (i.e. abortion). The doctors are evil maniacs who are putting thousands of babies in hell. Maybe we should do something to defend those babies? God wants us to do something to save His babies! If we don't save His babies we are evil and he will put us in hell!

You see, the problem is that in this worldview shooting up doctors at planned parenthood is a most moral action.

Now imagine that you sincerely believe in the following metaphysics. We are living in the Matrix, but this Matrix is a bit different than the one in the movie in that to leave it you don't pick up a telephone, but you have to die. This Matrix has been set up by the Creator to test you. If you obey his commands you will get eternal bliss in heaven when you exit the Matrix, and otherwise you get eternal suffering in hell. What are the Creator's wishes? He hates the Infidels. He hates that they publish cartoons to make fun of Him. He hates their societies are filled with sex, personal enrichment, and lack of devotion to Him. He hates that they occupy Jerusalem, His holy city. He hates that there is no worldwide Caliphate. He has written in his book that to ensure a place in heaven you can kill infidels. You get 72 virgins in heaven, and you get to pick a dozen people from your family who will also get a place in heaven. So what is this guy thinking while shooting up random people in a theater in Paris? He is counting the kills, and the Creator is counting with him. The number of people he kills will determine how much the Creator will love him. When he has killed enough he presses the button on his suicide vest to teleport into heaven, and start selecting family members to ensure their place in heaven when they die.

This Jihadist suicide cult worldview is the #1 problem, and people keep writing articles about income inequality, climate change, foreign policy, etc. No doubt these are contributing factors, but when are we going to address the elephant in the room? This is not something that only the mentally ill can believe in. This is a mind virus that can spread. It has spread. Polls show that about 10% of Muslims worldwide support ISIS, that is 160 million people. We need to stop it from spreading, for instance by encouraging competing pacifist mind viruses of moderate Muslims, empowering people who have a personal stake against this mind virus (women, gays, intellectuals, etc), educating people about different religions and atheism, stopping people who are spreading this mind virus (there are many Salafist and Wahhabist organizations that openly operate in Europe), and stopping their money streams coming from Saudi Arabia and other Gulf states, provide intense personal support to refugees and immigrants to make sure they integrate into the societies in Europe and the US and to make sure they learn the language, get European and American friends, don't live in closed parallel societies, etc.

You articulated your argument well (upvote!) and I don't disagree with a lot of it, but here is where we differ: why is it that this particular "mind-virus" is so much more transmittable than others? This is where I believe the other factors come into play. You basically agree with me when you start listing potential solutions to defeating the "mind-virus" in your last paragraph. The things you list are addressing the "other" factors. Education and support, for example, are things that help to close the inequality gap.

Indeed, there are factors that influence the susceptibility to this mind virus, but to understand the factors that influence it you first need to acknowledge that it is a religious mind virus. None of the articles that analyze this have acknowledged this (at least not the ones that I have read). That's partly because for atheists and moderates it's hard to imagine that somebody really believes that stuff, and partly because of political correctness.

An example why it's important to understand this is that the data shows that education in general does not work. Many terrorists are highly educated; a lot of them even have college degrees. So raising the general level of education is probably not effective. Education about religion might be.

Other important factors are tribal us-vs-them mentality, and (perceived) grievances.

You ask why this mind virus spreads so easily. That question is not very hard to answer: people are susceptible because they already believe that the Qur'an is the infallible word of God, and the things that ISIS does are sadly a plausible interpretation of the Qur'an. Such a belief in the infallibility is in itself dangerous, and I don't think we will have long term peace until the majority no longer believes that. Christians used to believe that about the Bible but the majority no longer does. Hopefully Islam can make a similar change, but I'm not very optimistic.