When you read the Quran even in another language you pose the question to yourself is the author of the Quran is God? Muslims who were born Muslims most of them have no second thoughts they know it is from God. They may not analyze it why but they know it is from God. It is like watching the TV they know it is a great invention and they know it is real though they do not know how it works. As Muslims get more sophisticated they started to analyse how it works and why people accepted over centuries the Quran. Those who barely read or do not read or write and those who are very sophisticated and highly educated. I will list here these thoughts why Muslims believe the author of Quran is God:
1- The dual speech: God speech to us in the Quran is telling facts on verses and talking to us directly on other verses. In order to understand that let me speak to you in this way "in the day times Maged goes to work and at nights Maged works on my computer, I would like all of you to know that". It sounds silly since the fact I mentioned about my life not that important or surprising. Besides, to speak directly again to you to emphasis it is not even worse to do that. For God the dual speech is very logical and wise. examine these verses:95:4 We have indeed created man in the best of moulds,95:5 Then do We abase him (to be) the lowest of the low95:6 Except such as believe and do righteous deeds: For they shall have a reward unfailing. 95:7 Then what can, after this, contradict thee, as to the judgment (to come)? As you read through it: verses 95:4,5 are facts that God is telling, while the verse 95:7 God turns to us and speak directly to tell us another fact pose it as question. So he makes you feel it is speech and not story telling and he turns to you every now and then to get your attention. When you read the Quran with this dual speech in your mind you will enjoy it and you will also feel it is a living text. It also takes Muhammad (PBUH) out of the picture he is like you and me an audience, He is the messenger that delivered the message to your home. Though God talk to him specifically in some of the verses in most part it is direct speech to all of us. When he use the word say in most part it is for him and us.
2- The Fatra: which is an Arabic world means the inner instinct that we born with. It is like the baby who smiles when you make funny voices. It is as innocent as his smile we have the same fatra we are born to seek God. Quran describes this fatra in us well and assert it in the verse:13:28 those who believe, and whose hearts find their rest in the remembrance of God - for, verily, in the remembrance of God [men's] hearts do find their rest-:So God who created us reminds us of this fatra.
3- The Confirmation: God asserted he is the author of the Quran and this what you expect from God to be the best witness to the truth.2:2 THIS DIVINE WRIT - let there be no doubt about it is [meant to be] a guidance for all the God-conscious.
4- The Dual Perception: God invites us to think with our minds and feel with our hearts his message of the Quran. That is what you expect God to do he wants you both mentally and spiritually to recognize him.22:54 And [God renders Satan’s aspersions null and void] so that they who are endowed with [innate] knowledge might know that this [divine writ] is the truth from thy Sustainer, and that they aught believe in it, and that their hearts might humbly submit unto Him. For, behold, God does guide onto a straight way those who have attained to faith.
5- The Perfect God: God described himself in the Quran by great names and attributes that is above any religious book.59:24 He is Allah, the Creator, the Evolver, the Bestower of Forms (or Colours). To Him belong the Most Beautiful names: whatever is in the heavens and on earth, doth declare His Praises and Glory: and He is the Exalted in Might, the Wise.
6- The All Knowing God: not only man but all creatures he knows its sustenance, expiration and deposition.11:6 And there is no living creature on earth but depends for its sustenance on God; and He knows its time-limit [on earth] and its resting-place [after death]:
7- The Complete Faith: God as the author of the Quran requires our worship, life and death all for him.6:162 Say: "Behold, my prayer, and (all] my acts of worship, and my living and my dying are for God [alone], the Sustainer of all the worlds,
8- The Matrix: God as the author is not writing to us a history book or scientific book. It is not a book of law or creed alone. It is all of that and more. As you expect it, independent verses that carry the truth placed side by side. It is more of a speech in it he talks to us proving his existence, his demand for worship, the history of prophets, the large universe, the scientific facts, the moral code and the laws. He navigate through them with authority and great ability.
9- The Frames: The wonderful thing about Quran is there are large amount of verses each can stand as evidence to God or expression of Wisdom that Muslims put it in large frames at their homes or work places. It is like the author knew that his verses will be in our homes and work places as they will be in our hearts. Here are few examples:16:18 And if ye would count the favor of Allah ye cannot reckon it. Lo! Allah is indeed Forgiving, Merciful.59:22 He is Allah, than whom there is no other God, the Knower of the invisible and the visible. He is the Beneficent, the Merciful.64:13 Allah! There is no God save Him. In Allah, therefore, let believers put their trust.
10- The Challenge: If God is the author he would challenge us and any one to prove the opposite:"This is indeed a Quran most honourable, a Book well-guarded...a Revelation from the Lord of the Worlds." (Quran 56:77-80)"This Quran is not such as can be produced by anyone other than God." (10:37)"Do they not consider (ponder over) the Quran (with care)? Had it been from other than God, they would surely have found therein discrepancies". (4:82)
11- The illiterate Prophet: the prophet did not read or write. Even if were able to read and write and had a computer at home he would still make mistakes and he would not able to find scientific facts that were proven in the future. People in fact did see him at the time of inspiration when God would sent him the verses of Quran. No one saw him thinking, studying, writing, editing, reviewing or copying the verses of Quran. There is no drafts and no second or third attempts. The words comes from his mouth and that is it.
12- The puzzle: the Quran was not a text in Muhammad house it was written on various objects. There were no papers to write and it did not come to him chapter by chapter but verses of different chapters and one of the chapters actually came in pieces over 10 years. The Quran was inspired over 23 years all together. It is like a puzzle it comes few verses from this chapter and then other verses from other chapter and so on. Muslims would write each time the inspired verses. After Muhammad death the Quran was actually collected and the puzzle was completed and he did not have a copy of it.
13- The Prophet Name: He was mentioned by name in the Quran only five times whereas Jesus Christ's name was mentioned 25 times. Could the Prophet go to such an extent of honouring someone more than himself if he had written the Quran? Similarly there is a chapter in the Quran entitled and dedicated to "Mary", the mother of Jesus Christ, while there is no chapter called, or dedicated to, the Prophet's own mother, Aminah, or daughter, Fatimah, nor were their names mentioned in the Quran. Could this have happened if the Prophet was the author of the Quran?
14- The critic Of the Prophet: in few verses God had criticized the prophet. You suspect if he was the author of the Quran he would not do that to himself.
15- The Quran Effect: The ability of the Quran to cause Islam to spread to 1.3 billion people, to have millions of people memorize all the Quran or great portions, the translation of the Quran to most languages and the millions of copies over the years attest to its author.
16- The Scientific Miracles in The Quran: find in my web and Internet the details of theses miracles.
17- The default: if people had failed to prove that Muhammad is not the author of Quran ( they said crazy, his personality was very stable and the Quran is full of wisdom, poem writers he never did write them and did not read or write, he was a lire he is name before the message was the honest and trustworthy, Magician he did not do magics and the Quran convince and does not delude, possessed by Satan or Jinn the message is that of a God not of the devil). Similarly if they proved to be unable to come with a book like the Quran or one of its chapters. By default it is from God.