Extraordinary claims require extraordinary evidence. When we look at the actual history of the Quran--and it has one, just like any other book made my human hands--we find that the claims of its unaltered perfection don't look very plausible: http://www.theatlantic.com/magazine/archive/1999/01/what-is-...

"As Muslims increasingly came into contact with Christians during the eighth century, the wars of conquest were accompanied by theological polemics, in which Christians and others latched on to the confusing literary state of the Koran as proof of its human origins. Muslim scholars themselves were fastidiously cataloguing the problematic aspects of the Koran—unfamiliar vocabulary, seeming omissions of text, grammatical incongruities, deviant readings, and so on. A major theological debate in fact arose within Islam in the late eighth century, pitting those who believed in the Koran as the 'uncreated' and eternal Word of God against those who believed in it as created in time, like anything that isn't God himself. Under the Caliph al-Ma'mun (813-833) this latter view briefly became orthodox doctrine. It was supported by several schools of thought, including an influential one known as Mu'tazilism, that developed a complex theology based partly on a metaphorical rather than simply literal understanding of the Koran."

The claim that thousands of people committed the entire Quran to memory during Mohammad's lifetime--a time when the finished product didn't actually exist by most accounts--and then produced a generally agreed-upon version in an unbiased way is enormously implausible.

Please note clearly: I am not saying that "thousands of people memorizing a book of seventy-odd thousand highly-repetitive words" is particularly implausible. As a feat of memory this is rather modest and uninteresting. That's completely unrelated to my point: as you say, a child of ten could do it. Big deal.

What I'm saying is the claim that the book was complete and that there was unbiased agreement in the production of the written version based on many memorized versions is extremely unlikely given everything we know, and that there were such vigorous debates about the issue amongst early Muslims themselves makes it even more-so. Certainty about historical events rarely increases with time, and Muslims have done very little of the hard scientific work required to plausibly claim they know more about what happened in the 7th century than Muslims of the 8th and 9th did. They have in fact actively attacked and sometimes killed people who have dared to undertake any of that work.

Furthermore, one of the most bizarre aspects of the Quran is the ordering of the suras, which is based on no literary or philosophical or temporal principle but (more-or-less) how long they are. Take the Bible and reorganize it that way and it would become even less coherent than it already is. So Muslims have to claim that the book is perfect, but its organizing principle is completely incoherent. God is supposed to work in mysterious ways, but this kind of incoherence is a good deal more consistent with human agency and the historical development of the final text under the auspices of ignorant men who were guessing at how best to put it all together.

One final note: killing me does not change the truth or falsity of anything written above. Why I feel obliged to say that should be obvious to anyone who is remotely honest and aware, Muslim or non-Muslim. I believe everyone who is critical of Islam or the Quran should include a statement of this nature. It does not reduce the already-small chance any of us will get killed, but it will remind everyone that for every voice that speaks out there are many more that stay silent because they know that some deeply sincere religious person acting in accordance with the highest example of their prophet may murder them if they speak.