To avoid having to endure the consequences of your own actions. For people with nothing to lose, suicide attacks are actually the most risk-averse choice: regardless of the possible existence of an afterworld, you're certain to escape punishment in this world. Look at Columbine-style attacks - no religion there, just semi-rational choices.
People don't blow themselves up because a book or a preacher tells them so; they do it because they are fed up with living shitty lives (either in material or spiritual terms). That is what education should bring them: the consciousness that there is always something worth living for. At that point, whether god exists or not, it doesn't matter.
Frankly, I suspect that at least part of this comes from the aversion of highly educated and rich people to the idea that somebody much like them in those respects could do such a thing, and that it must be a poor lowly educated person doing it.
My second statement is coherent with this view: what education should give people is such a rooting. This is not necessarily what it does currently give them. In fact, a lot of academic tracks do their best to kill off any ounce of sentimentalism in one's heart. If it's really "all about data", killing a few hundreds "for the greater good of billions" doesn't look like such a terrible choice. This is something we really should keep in mind.
If true we would expect terrorists to be more lowly educated and poor people who mainly come from countries that have suffered under the west. We would expect these to be people who hate life, not people who love death. We would expect terrorism to be weakly or not at all correlated to religion. We would expect that the terrorists are not explicitly telling us that they're doing it because of religious dogma. We would expect terrorist groups to be fighting against the west, and not mass murdering Yazidi's for example, who have absolutely nothing to do with what happens in the world. Of all western countries, we would not expect these attacks to be against France so many times. Why have previous attacks and outrages focused on cartoonists? I could go on and on. What we actually observe is the opposite.
All of this is explained perfectly well by the second theory.
These usually get planned well in advance by some very sick people who are trying to kill as many people as they can and go out in a blaze of glory. Sure, the existence of opportunistic terrorists networks that get these people to coordinate their attacks and stamp a ideology on them tends to mean that the one day body count is higher for a particular incident. Still, the body count per attacker is often comparable, it's just that the attacks happen on the same day instead of a few weeks apart.
But yeah, if we ignore the non-Muslims who do things like this we can say it's all the fault of Muslims.
> Of all western countries, we would not expect these attacks to be against France so many times.
And why not? They have been among the most brutal colonial powers, with shocking behaviour in Northern Africa and ongoing active military engagement across Africa -- in large part because of their ideological bent on absolutist superiority of the French republican model. They actively worked to blow up Lybia and actively support anti-islamic forces there. And of course they have now joined the anti-IS bombing campaign, because they hate to be left behind when there is to engage around the Mediterranean Sea. All the while, they have huge swaths of disenfranchised 2nd and 3rd generation-immigrant youth in their midst that they simply don't know what to do with. They are the easiest target after the UK, but unlike Britain they are not an island, their borders are very porous, and their security services are clearly less effective than the Five Eyes axis. On top of that, this: http://www.theguardian.com/world/2015/nov/14/france-active-p...
Still, people don't find it inappropriate to bring up Columbine when they talk about VTech or Aurora. When people try very hard to exclude all the other mass attacks and single out only the ones connected to Islam in situations like this speaks more to their personal biases than anything else.