I am afraid I am going to repeat some of the things I have already mentioned in individual messages, but I do believe one should try not to take the documentary approach to this short story, or at least not exclusively. I am not sure that, to quote Jillian, "testimonials have a lot more meaning". Their meaning is different or cannot be worked out according to the same criteria as the meaning of a work of fiction. Of course, there is a plausible evocation of a context, and of course some details are verifiable. But there is too much taste for hyperbole for the realistic aspect not to be jarred (that is what Andrew points out as regards the inordinately long period of constipation -- to put it quite literally -- which together with the Holy Volvic bit, is a piece of pure decrowning/debunking of the institutional uses of religion and belongs to a very long tradition in some Christian traditions -- I am thinking of the Roman Catholic confession here).
Secondly, I am not sure that (pace Andrew) Muhammad Atta really believes in the cause. There is textual evidence that he has seen through the Sheik's lies and some dogmatic obfuscation (I am referring to the Virgin/raisin episode). This is why M. Atta is such a complex figure in this text, a figure that hovers somewhere on the dividing line between humanity and monstrosity. Hence the strong destabilisation performed on the reader, this being buttressed by the internal focalisation and unmediated access to the protagonist's thought content. The target is less Muhammad Atta than the fundamentalist position he is conditioned into espousing.
Justine has pinpointed a central teme; i.e. : boredom. In this context it is less some sort of metaphysical ennui than, paradoxically, a motor of urgency and narrative countdown.