Image: Donated by Brooklyn Museum, USA
This only happened once, apparently. Although spread over some 23 years, there is no record of Allah revealing the same thing several times, least of all the entire Qur'an.
You'll most likely be told that the proof that it is Allah's revealed word is the fact that Muhammad was illiterate and yet was able to write the Qur'an in perfect classical Arabic; that Allah literally guided his hand. This is, of course, the 'lie to children' version. The accepted version amongst Islamic scholars is that Muhammad never actually wrote anything of the Qur'an. Instead, the words came to him as 'revelations' over a period of some 23 years and were taught to his followers as oral traditions, only being written down after his death, on the instructions of the first caliph, Abu Bakr.
Based on earlier transmitted reports, in the year 632, after the demise of Muhammad a number of his companions who knew the Quran by heart were killed in a battle by Musaylimah, the first caliph Abu Bakr (d. 634) decided to collect the book in one volume so that it could be preserved. Zayd ibn Thabit (d. 655) was the person to collect the Quran since "he used to write the Divine Inspiration for Allah's Apostle". Thus, a group of scribes, most importantly Zayd, collected the verses and produced a hand-written manuscript of the complete book. The manuscript according to Zayd remained with Abu Bakr until he died. Zayd's reaction to the task and the difficulties in collecting the Quranic material from parchments, palm-leaf stalks, thin stones and from men who knew it by heart is recorded in earlier narratives. After Abu Bakr, Hafsa bint Umar, Muhammad's widow, was entrusted with the manuscript. In about 650, the third Caliph Uthman ibn Affan (d. 656) began noticing slight differences in pronunciation of the Quran as Islam expanded beyond the Arabian Peninsula into Persia, the Levant, and North Africa. In order to preserve the sanctity of the text, he ordered a committee headed by Zayd to use Abu Bakr's copy and prepare a standard copy of the Quran. Thus, within 20 years of Muhammad's death, the Quran was committed to written form. That text became the model from which copies were made and promulgated throughout the urban centers of the Muslim world, and other versions are believed to have been destroyed. The present form of the Quran text is accepted by Muslim scholars to be the original version compiled by Abu Bakr.
This of course destroys the argument that the fact that an illiterate man suddenly 'wrote' the Qur'an is proof that it came from Allah, but, like other religions, Islam seems capable of believing two or more mutually incompatible things simultaneously. But, whichever version you prefer, both end up with a supposed single original Qur'an. The belief is that this was then used as the master copy from which other copies were made, initially as personal copies for important figures.
And in the Qur'an, there is an explicit and unambiguous declaration, supposedly by Allah, that he personally will protect and guard the Qur'an.
Indeed, it is We who sent down the Quran and indeed, We will be its guardian.
So the Qur'an then, even more so than the body of Muhammad himself if ever it were to be found, is the most precious thing imaginable to a Muslim. Their entire religion comes from the words in it and the words are the words of Allah himself. The entire power and authority of the early imams and caliphs comes from it. It is at the very centre of the Muslim Universe and some even argue that, along with Allah, it has always existed and was never created, merely revealed.
It is inconceivable that such a sacred object would be casually disposed of, thrown out with the rubbish or cast aside and forgotten to decay into dust and disappear. It is almost inconceivable that it would be stolen or broken up and the pages recycled or used for some less important writing. It is inconceivable that some disaster like a fire, a flood or an earthquake would have destroyed it without at least some record of this disaster being made.
And it even has the indestructibility of being protected by Allah, doesn't it?
So where is this original Qur'an? Where is the book originally either dictated to Muhammad with his hand divinely guided, or the original 'authorised' version compiled under Uthman ibn Affan or the Abu Bakr version given to Hafsa bint Umar, Muhammad's widow, to look after?
In short, where is the most precious; most sacred object imaginable to any Muslim; a book protected by Allah himself, the original Qur'an? Did they just lose it but forgot to record that fact? Did it just go missing but nobody noticed? Did Allah fail to protect it and allow it to be destroyed?
Somehow, someone needs to explain why the original Qur'an is missing.