Answer

The Quran was revealed piecemeal throughout a period of about 23 years. The Prophet received the first revelation in 610CE, in the Cave of Hira in the Mountain of Light (Jabale-Noor), two and a half miles away from the House of Allah in the city of Makkah in Arabia.

The Quran is the Word of God delivered by the Archangel Gabriel to Prophet Muhammad (Peace be upon him). During the life of prophet Mohammad PBUH his companions wrote the Quran but it was not compiled into one book. Right after the death of prophet Mohammad PBUH, the Quran was compiled into one book. This book is preserved until today.

Compilation of the Quran
The Quran was revealed piecemeal, according to the needs of the time. Angel Jibrail [PBUH] brought it to the Prophet [PBUH] who would memorize it. Afterwards, it was preserved in two ways.

First, through memorization, there were a number of early Muslims who would memorize each revelation as soon as it was revealed and thus had the whole Quran memorized at the time of the final revelation. The tradition of memorizing the entire Quran still continues, and a person who does so is called a Hafize Quran.

Second, the Quran was preserved through writing. Whenever any revelation took place, it was written at once on tablets, palm branches, shorn of leaves, or animal skin. This was done primarily by Zaid bin Thabit, who was the main scribe out of the 42 scribes of the revelation. The Prophet [PBUH] set the order of the chapters under the guidance of Angel Jibrail [PBUH] and ordered his companions to maintain that order. Abu Bakr, the first caliph of Islam, compiled the Quran, and Uthman, the third caliph, made numerous copies and sent one copy to each state capital.


It is the true word of God as is proved in the following lines.
Proofs and Evidences that Quran is from Allah (swt):
1. Quran says it is from Allah:
The revelation of the Book (Quran) is from the Lord of the worlds (21:2)

2. Challenges:
The Quran gave a challenge to the whole world that if they are so competent they should bring another Quran in the following verse: Produce a Quran like it (17:88)
But so far no one has been able to put up another Quran.

Then Quran lowered the challenge respectively and even then no one put forward his/her version of Quran

Produce 10 Suras (verses) like it (11:13)
Produce One Sura (verse) like it (10:38)
Produce One Sura (verse) somewhat comparable to it (2:23)


Thus is means that it is a Divine word that no human has been able to produce a Quran.

3. No Contradictions:

Also, Quran is free from any contradictions and this is a proof that it is not coming from a human but from God himself.
"Don't they ponder over the Quran, had it been from anyone besides Allah, they would surely have found therein many contradictions (4:82)


4. No crookedness:
An Arabic Quran without any crookedness...(39:28)

5. Prophecies fulfilled:
Many of the prophesies in Quran have been fulfilled. And it is not possible for a person to see so much further into the future to make that exact a prophecy. Thus it means that it is from God.

Victory of Rome over Persia (30:2-4)
Allah makes superpower of those Muslims who believe and do good works (24:55)
Islam will prevail over all other religions (48:28)

6. Answer to every question
Every time they come to you with an argument, We bring you the truth and
the best of explanations. (Qur'an, 25:33)
7. Solution to every problem
O mankind! there hath come to you a direction )QURAN) from your Lord and a healing for the (diseases) in your hearts,- and for those who believe, a guidance and a Mercy. [ Al-Quran 10:57]

8. Scientific facts: See page on Quran and Science

Non muslim Quranic experts attribute the Qur'an in its form today to post-7th Century
alterations. The consensus is, "independent scholars studying the Qur'an and Hadith, have concluded that the Islamic scripture was not revealed to just one man, but was a compilation of later redactions and editions formulated by a group of men, over the course of a few hundred years. The Qur'an which we read today is not that which was in existence in the mid-seventh century, but is a product of the eighth and ninth centuries. It was not conceived in Mecca or Medina, but in Baghdad."
Because the origins of Islam and the Qur'an are dubious. This is the opinion of renowned scholars and professors of Islam, history, Arabic and many other fields. Among them - Dr. John Wansbrough, American historian who taught at London University's School of Oriental and African Studies; Professor Joseph Schacht, professor of Arabic and Islam at Columbia University in New York and a leading Western scholar of Islamic law; Dr. Patricia Crone, a scholar, author and historiographer of early Islamic history working at the Institute for Advance Study; R. Stephen Humphreys, professor of history and Islamic studies at the University of California at Santa Barbara; and Professor Andrew Rippin, professor of history and specialist in Islamic studies at the University of Victoria, B.C., Canada
"Almost universally, independent scholars studying the Qur'an and Hadith, have concluded that the Islamic scripture was not revealed to just one man, but was a compilation of later redactions and editions formulated by a group of men, over the course of a few hundred years. The Qur'an which we read today is not that which was in existence in the mid-seventh century, but is a product of the eighth and ninth centuries. It was not conceived in Mecca or Medina, but in Baghdad. It was then and there that Islam took on its identity and became a religion. Consequently, the formative stage of Islam was not within the lifetime of Muhammad but evolved over a period of 300 years."
Gerd Puin on Qur'anic Integrity
Gerd Puin, a German scholar and the world's foremost authority on Qur'anic paleography, the study and scholarly interpretation of ancient manuscripts. He is a specialist in Arabic calligraphy:
"My idea is that the Koran is a kind of cocktail of texts that were not all understood even at the time of Muhammad. Many of them may even be a hundred years older than Islam itself. Even within the Islamic traditions there is a huge body of contradictory information, including a significant Christian substrate; one can derive a whole Islamic anti-history from them if one wants. The Qur'an claims for itself that it is 'mubeen,' or clear, but if you look at it, you will notice that every fifth sentence or so simply doesn't make sense. Many Muslims will tell you otherwise, of course, but the fact is that a fifth of the Qur'anic text is just incomprehensible. This is what has caused the traditional anxiety regarding translation. If the Qur'an is not comprehensible, if it can't even be understood in Arabic, then it's not translatable into any language. That is why Muslims are afraid. Since the Qur'an claims repeatedly to be clear but is not-there is an obvious and serious contradiction. Something else must be going on."
[Hint:

1.


Quran as said above includes events that happened before Islam and before prophet Muhammad birth for two reasons: first as a proof that Quran is God revelation from God, otherwise how the prophet will know these events. Second, for Muslims to gain from these events wisdom and advice]
2.

Quran is a miracle in its Arabic wording and Arabic structure and challenged the Arabs to write even only one verse similar to it. That is why any translation of Quran into other languages is considered as translation of its meaning and not exactly translation of its wording. There are currently Quran meaning translations almost in all world live languages.
3.

Quran has lots of scientific statements that its validity were only proved by nowadays scientific evidences and discoveries. This scientific miracle is a proof that Quran is not human written and that Quran is God revelation.]


Imperfect Qur'an
Another reason why the Qur'an fails the criteria as the word of a perfect God is because of the imperfections within the Qur'an. The Qur'an is riddled with literary contradictions, scientific errors and historical errors.
[ hint: Challenge to give only one example of a single scientific or historical contradiction or error. It is the opposite the historical and scientific authenticity of Quran are proofs that Quran is not human written text]
Plagiarism in Muhammad's Time

The Qur'an tells us that Muhammad's critics caught him plagiarising traditions, folklore and Jewish and Christian scripture. Examples: "We have heard this (before): if we wished, we could say (words) like these: these are nothing but tales of the ancients" (8:31). "Such things have been promised to us and to our fathersbefore! They are nothing but tales of the ancients!" (23:83)"
[ Hint: Quran explained the alterations in older holy book texts. The verse above is the sayings of the unbelievers that Quran explains it would be said by them. If you continue with the following verses you will understand it better.]
Zoroastrians Traditions

In regard to the Islamic versions of heaven, 'paradise', plagiarism from non-Abrahamic beliefs is also evident. "None of this, of course, can be found in the Jewish or Christian Scriptures, but it is in the writings of the Zoroastrians of Persia, who were a considerable presence in the areas around the Persian Empire before the advent of Islam. According to historian W. St. Clair Tisdall, who did pioneering work on these questions in his monograph "The Sources of Islam," which he later expanded into a book, and in his other writings, "the books of the Zoroastrians and Hindus... bear the most extraordinary likeness to what we find in the Koran and Hadith. Thus in Paradise we are told of 'houris having fine black eyes,' and again of 'houris with large black eyes, resembling pearls hidden in their shells.'... The name houry too is derived from an Avesta or Pehlavi Source, as well as jinn for genii, and bihisht (Paradise), signifying in Avestic 'the better land.' We also have very similar tales in the old Hindu writings, of heavenly regions with their boys and girls resembling the houris and ghilman of the Koran.""
Source: The Truth About Muhammad by Robert Spencer (2006)
[Hint: God is the source of Quran and He is the same source of all revelations to all God prophets since Adam. It is logic to have some common words in God holy books or in other text books as extraction from Godf holy books]
Different Qur'ans in Muhammad's Time

Islamic sources tell us that Muhammad's followers would argue because Muhammad provided contradicting versions of the Qur'an. A notable example appears in Bulhari's Hadith:
"Umar bin Khattab [the second Caliph] said, 'I heard Hisham bin Hakim bin Hizam reciting Surat Al-Furqan ["Al-Furqan," the title of the 25th surah, has no meaning in any language.] during the lifetime of Allah's Apostle. I listened to his recitation and noticed that he recited it in several ways which Allah's Apostle had not taught me. So I was on the point of attacking him in the prayer, but I waited till he finished, and then I seized him by the collar. "Who taught you this Surah which I have heard you reciting?" He replied, "Allah's Apostle taught it to me." I said, "You are lying. Allah's Apostle taught me in a different way this very Surah which I have heard you reciting." So I led him to Muhammad. "O Allah's Apostle! I heard this person reciting Surat-al-Furqan in a way that you did not teach me." The Prophet said, "Hisham, recite!" So he recited in the same way as I heard him recite it before. On that Allah's Apostle said, "It was revealed to be recited in this way." Then the Prophet said, "Recite, Umar!" So I recited it as he had taught me. Allah's Apostle said, "It was revealed to be recited in this way, too." He added, "The Qur'an has been revealed to be recited in several different ways, so recite of it that which is easier for you." (Bukhari:V6B61N561)
[Hint: Those who claim that prophet Muhammad provided contradicting versions of the Quran and take the prophet saying above as evidence, they don't understand the word 'recite' or pretend that you don't understand this word to make a false evidence. There is difference between reading the Quran and reciting the Quran. Reading means saying the Quran words as written. Reading the Quran is the same with no single world alterations since Quran revelation and until last day of Judgment. It is maintained, by God will, without single letter change because holy Quran is last words of God revelation to mankind. However, different recitations of Quran means different tones or composing when reading the Quran. The Quran wording is the same (when reading) but the tone of Quran reading (reciting) has different agreed upon forms.]
Devoid of Context
The Qur'an in itself as a source for anything is devoid of context and thus arbitrary. Being devoid of context and any understanding, how can it be understood as the word of God?
"We do not have material in the Qur'an to compose a biography of Muhammad because the book is a disjointed discourse, a pastiche [imitation, parody] of divine monologues that can be assembled into a homily [lecture, sermon] or perhaps a catechism [snippets of dogma] but that reveals little or nothing about the life of Muhammad and his contemporaries.... The Qur'an give us no assurance that its words and sentiments are likely to be authentic in the light of the context they were delivered and in the manner of their transmission. There are no clues as to when or where or why these particular words were being uttered.... The Qur'an is of no use whatsoever as an independent source for reconstructing the life of Muhammad. The Qur'an is not terribly useful even for reconstructing the Meccan milieu much less the life of the man who uttered its words; it is a text without context."
Source: Jay Smith, "Is the Qur'an the Word of God?" A debate between on the Qur'an hosted at Trinity College, Cambridge and Dr Jamal Badawi in 1995
[Hint: The wording above is evidence that Quran is God revelation to prophet Muhammad and not human text writing. Although Quran has an independent chapter called Mariam (the Virgin Mary) and full chapter on the history of prophet Joseph the son of prophet Jacob, Quran doesn't contain single verse describing biography of prophet Muhammad or his marriage and doesn't contain the name of his father or wife or mother or anyone of his family. Quran is God words that directed for leading Muslims to the right path of God worship and human kind benefit and not historical text book].
Answer


The Qur'an was the recitations of Muhammad and recorded by various scribes.
Answer

The Qura'an is the Word of God delivered by the Archangel Gabriel to Prophet Muhammad (Peace be upon him).
The Qura'an is to be the book of divine guidance and direction for mankind, and consider the original Arabic text to be the final revelation of God All Mighty.

The early religions before christians began, were out of God's will!If the truth from the bible were not written via the prophets and apostles of God of Abraham,Isaac and Jacob/ almost all humans will disappear as a result of transgressions against the holy will of GOD.take note that when men were created by YhWh ALYm, the sons of transgressors also mingled with women in order to contaminate the DNA of true humans with impurities(serpent traits)!and by this virtue, two forms of humans existed, the elect of Holy God and the sons of transgressors!The holy scriptures were written for the elects of GOD and for those who will be called to believe in God through HIS son jesus Christ!If the people of present era will disregard the truhtfulness of the holy scriptures of YhWh (the bible), the laws governing the existence of humans will take effect for the believers and non believers.The seeds of truth are not conforming with the seeds of deceitfulness!The truth shall prevail!