Lastly : The Refuations of that claim
( There are already two above )
3) Quran is definitely from God . God told us that us : " We have, without doubt, sent down the Message; and We will assuredly guard it (from corruption). " Al-Hijr . It is enough , I believe , for a Muslim to know that God commanded or said something to believe & abide Immediately .
4) We have various Qiraat within the same frame of the same Book , and the same content . We do not , for instance , have the Quran of Hafs or the Quran of Nafei نافع . We have the Quran of Allah , revealed to the Prophet . We have the Qiraat of Nafei & Hafs & ... that have been proved to have been approved of by the Prophet . ( in other words the reliable Qiraats proven to have dated back to the time of the Prophet , Like Sahih Hadith proven to have been said by him )
5) Whoever argues that Quran is not the Word of Allah but of Muhammad - God Forbid - this is a good timing to refute this briefly :
* Despite these variations in Qiraat or the seven Ahruf , The Quran still maintained its coherence for over 14 or 15 centuries . It is still understandable without any thing out of place . If anyone is able to go through the abundant examples of variations , he will recognize that this is not intended only to facilitate , but also to prove that Quran is the Word of Allah , and manifest another miracle & inimitability of the Quran .
If Quran was indeed a fuman outcome , it could not have retained its appeal & applicability in such a flowing reasonable way . It is cleary the Word of the Creator who knows very well what is understandable & believable for the minds and hearts of His creatures .
* Surat Al-Masad is another conclusive evidence . This Sura was revealed during the lifetime of Abu Lahab , not after his death . It dooms him to eternal Hell . Well , Abu Lahab could just embrace Islam - even if pretending -to indicate that Muhammad is - God forbid - a liar ! But Abu Lahab died as a Kafer & did not convert . How could the Prophet have been so sure that Abu Lahab would nover convert to Islam ?? It must be from the only Power in the whole universe who can know the unknown , predict all future because He KNOWS all future , past & present ... Who could it be but God ??!!!!
We'll have to leave it there because we could just continue forever .
That is the best I could present . If I am right , it can only come from Allah " In Him I Trust, and unto Him I look " . If I commit a mistake , it is my own flaw , I ask God to forgive me .
Peace be ipon you all ,