An interesting article on the origin of the Quran:
Since Muhammad and his several hundred companions were completely illiterate (could not read or write) and Muhammad had a poor memory; thus, his companions memorized for him the Quranic verses they plagiarized/concocted. But in the battle of Yamamah, almost all his companions were killed and the original Quranic verses were lost forever and was never compiled in writing before Muhammad himself was killed by food poisoning in 632 A.D. by a Jewish slave, who said, “If you are a true Apostle, Allah would have saved you”. Caliph Abu Bakr (632-634A.D.) then entrusted Zayed Ibn Thabit to compile the Quran, from memories of Muhammad’s illiterate wives, concubines, slaves, and a few contacts; who claimed to have heard Muhammad and his companions utter various verses. Zayed managed to gather an estimated 7,900 verses. But this first compilation of the Quran, with numerous contradictions, ridicule, confusions, and errors, created a lot of trouble and huge problems arose over the years. Under the caliphate of Uthman (644-656 A.D.), he was compelled to withdraw all the distributed, handwritten copies of the Qurans and burnt them. Zayed was again ordered for the second time, to recompile and re-edit the Quran more sensibly and convincingly from his original Quran, kept with Hafsa (Muhammad’s widow). Zayed did the best he could in re-editing the Quran and more than 2,000 contradictory, confusing, erroneous and illogical verses were abrogated (cancelled), some were replaced, and others added/borrowed to make sense of the cancellations/replacements. This re-edited Quran in Sura 16:101-103 says Arabs accused a Christian slave of teaching Muhammad and was persecuted, and 25:4-5 confirms accusations of borrowing stories from Folktales, and Fables by the then Arabs. Abu Al-Aswad Al Doaly put dots as syntactical marks, during the time of Mu’awiya Ibn Abi Sufian (661-680 A.D). The letters were marked with different dotting by Nasr Ibn Asem and Hayy ibn Ya’amor, during the time of Abd Al-Malek Ibn Marawan (685-705 A.D). A complete system of diacritical marks, (damma, fataha, kasra,), were newly created by Al Khaleel Ibn Ahmad Al Faraheedy (d. 786 A.D). Now the Quran stands at only 6,241 verses today from its original 7,900. But given the circumstances prevailing in those days and the fact that compiling from various uneducated peoples’ memories, etc; this concocted manmade Quran, still have a lot of contradictions, confusions, absurdities, illogicalities, ridicule, errors, unscientific theories, etc. (For details, see ‘A dialogue between a Christian and a Muslim about the Quran’ and ‘A balanced understanding of Islam’ in this website). So a lot of people did have a hand in inventing the Quran. Thus, the bulk of the verses of today’s Quran, are actually from Muhammad’s wives, concubines, temporary wives, slaves and was edited by Zayed Ibn Thabit (it has nothing to do with God).