People still do not believe or do not want to believe how hard to come up with a a book like the Quran. Take this example suppose today I want to declare that I am prophet Taman and I made a book like the Quran. See what I have to go through:
1- I need to be the perfect liar. It means that I have to convince all people for 23 years around me of my message even my wife and children. The conflict will come here. As a perfect liar, I would be a well known liar. You can not lie to all the people all the time. You will find someone that found a lie that I had done. Or if I am very honest and decided to make great lies for 23 years against God people will easily read my face. Honest people are easily red if they lie from my experience. It is very difficult to be a selective liar to lie about a message that would consume more than 80% of your functional life and be honest in the other 20%. Prophet Muhammad is known for his honesty before and after the message.
2- I need to make it up first. I would not just go out one day and say an angel of God came to me and then get verses every few days. I may try to make a book like the Quran first or big chapters to be sure of my abilities. Even though someone will catch me thinking of the verses or writing them down in a piece of paper. Prophet Muhammad did not know how to write or read. People saw him during the time the inspiration of God comes into him he would get clammy and then bring the miraculous verses of God.
3- I would be consulting the torah and gospels before I would write this book. A lot of people would know my interest in that early on. Prophet Muhammad was not known to be a scholar.
4- To make my book a linguistic miracle: I would have to be very good with poetry and I well be well known for my skill of language. Prophet Muhammad did not know how to write or read.
5- I would not think about scientific miracles for people who would come centuries after me so they believe in my book. Even if this crossed my mind how can I come up with miracles that people would find them true after 1400 years or so.
6- What will be my real belief of God: I would wander suppose there is a God and he discovered that I am writing a book and say it is from God I would be very fearful. Particularly, I believe there is other books from God. I would at least look confused. Prophet Muhammad looked a strong believer. It is just impossible to give faith to people if you do not have faith yourself. My fluctuation in faith does not come from the message of the Quran but from the personal and widespread injustices in the world. Or may be God wants me to feel this way for a reason.
7- To pray for long nights and fast and go for wars for a God that I created would be very crazy. Very early on people will know that I have paranoia. Even if it is only selective paranoia they will be smart enough to know this paranoia. When the jealous and corrupted Arabs at time of Muhammad were trying to suppress his message they would think and say to each other what would we say to people about him. Then they will say let us say he is crazy. If you note they did not say what we think ourselves about him.
8- Second book: To be more convincing is to bring other knowledge like the hadith that is different from the Quran. Miraculously I would need to be able to have the language style very different for the two books.
9- I need to fear God: by definition righteousness is the product of feeling the existence of God all time and fearing him so you do everything right in your life. Muhammad was known to be the most righteous of humans. So how we can reconcile his fear of God with lies against God. If we say he was himself deceived and the Quran is inspired by Satan. I would say read the Quran and talk to yourself am I really saying the truth or read in my blog: Is the Quran inspired by Satan?. You may say UFO inspired him. Call them and find out. UFO can not affect our spirituality, visions or prophecies. I do not predict that UFO would want us to worship God or be righteous. We do not even know what in hell this UFO phenomena all about.
