So yesterday I just read sure lahab and something has been disturbing me ever since, the surah feels as if it was written by a very angry person looking for a way to curse someone with more power than him, it does not feel like anything Allah would be saying which made me to start questioning how do we know that the Quran is really from Allah, why is it that there are verse that seem to be self serving to the prophet like verse 33:53 and 49:2, so I would like to know what specific verse or surah in the Quran has conceived you that the Quran is really for God not the prophet a verse that you believe it is impossible to be said by a human of that time.
Al Massad / Al-Lahb (111), contain a curse to Mr. Daddy Of Flame and Mrs Daddy Of Flame.
It seems the author was very angry with both of them yet there's no explanation of the context of what Mr and Mrs Daddy Of Flame do which caused the author to be so angry with them.
A dig up to the 'tradition' doesn't reveal any 'sound' reason either, it was said that this Daddy Of Flame was Muhammad's uncle and often mocked and bullied Muhammad.
We met bully and mocker throughout our life, but we don't 'curse' them to be tortured by fire. That's so brutal.
Perhaps this Daddy Of Flame did something really horrible such as:
1. Brutal murder and torture
2. Sacrificing human to the Deities / Gods
3. Sacrificing his own children to the Deities / Gods
Which makes the author to lose his/her patience and utter such curse...
I personally don't know...
So yes, IMHO the book was clearly written by human.
Regarding who was the 'author(s)', I think it's definitely a being, a creature, as it took the perspective of one.
Some say it was the saying of an Angel named Gabriel / Jibreel
"Indeed it's the saying of honorable messenger, possessor of power with the owner of the throne, secure, one to be obeyed and trustworthy"-- 81:19-21
In other section (53:27) it seems the author is 'not happy' because some human named the Angels with 'female' names.
While regarding "From God", well given all things were created by God then all things were from God. Then all books, all ebooks, all scriptures, all scrolls are "From God".
I understand that the above line of thought will not makes those who idolize the Quran to be happy, as it goes against their objective to maker their idol (a book) to be superior / above all other books. That's why they make the claim that it's the only book authored by God and there will be no more revelation from God after that book was being written. They're trying to impose a belief that the only way one can found God's revelation is through that book which they idolize.
Speaking of book, written by human and claimed to be authored / inspired by Angel(s) as revelation from God.
I found another book(s), written within our era, where the author claimed she was told to wrote those books by Angels. She claimed she can see angels and talk with them on daily basis since she was born.
https://lornabyrne.com/shop/IMHO A book or other reading material doesn't need to have a claim that it was written by God in order to have 'truth' or something beneficial to our lives inside it. And definitely God's revelation hasn't ended ask any of your question to God and He will answer.