بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ
Of all the religious scriptures in existence today which are considered to be from inspiration of God by their respective followers, Al-Kitab is the only one in which God himself claims to be the author. No other book within itself claims to be the Word of God. Only their followers claim that they are from inspiration of God. Al-Kitab is the only widely recognized religious book which claims within the book, to be the Word of God.
39:1-2 تَنزِيلُ الْكِتَابِ مِنَ اللَّهِ الْعَزِيزِ الْحَكِيمِ إِنَّا أَنزَلْنَا إِلَيْكَ الْكِتَابَ بِالْحَقِّ فَاعْبُدِ اللَّهَ مُخْلِصًا لَّهُ الدِّينَ
The sending down of the Book is from Allah, the Exalted in Power, the Wise. Verily, We have sent down the Book to you in Truth, so serve Allah, making the Din/judgment pure for Allah.
2. There is no claimant on authorship of Al-Kitab except God, however, most of the people who don’t believe that Al-Kitab is Word of God, believe that it must have been written by Mohammad (pbuh). Obviously, if it were true, the main purpose of Mohammad would be to obtain glory for himself by pretending a prophet of God. However, what we find in the reading Al-Kitab is that it is all about focusing on God, and not on any personality. This sort of book would not have been written by any charlatan or fraudster seeking personal glory for himself. Mohammad (pbuh) is mentioned far less times in Al-Kitab than other messengers e.g Moses and Jesus. Compared to them, Mohammad is mentioned only a miniscule amount of time. In fact the prophet has been admonished in the Book at some places. Had Mohammad been the personality type that these people believe him to be and he be after false glory, he would have made himself the center of focus in the Book. Instead we find word ‘Mohammad’ mentioned only 4 times in Quran and word Ahmed as 1 time and all focus in the Book is on God (https://topicsfromquran.com/2017/03/12/making-dinjudgment-pure-for-allah/). In addition, The hadith books which are supposed to be sayings of Mohammad, can very easily be distinguished separately from Al-Kitab in literally style and content. If Mohammad would not have written Al-Kitab and nobody else claims to be the author of Al-Kitab, then this leads us to the conclusion that this is but the Word of God.
3. In Al-Kitab, Allah promises to protect the Remembrance (Az-Zikr) 15:9. People have put Al-Kitab in paper form (6:91). Again, Al-Kitab is the only religious scripture which does not have an accepted standard version. It is preserved with collective remembrance of the believers.
15:9 إِنَّا نَحْنُ نَزَّلْنَا الذِّكْرَ وَإِنَّا لَهُ لَحَافِظُونَ
Indeed, We have sent down the Remembrance; and indeed we are the guardians for it.
4. Al-Quran is a reading of Al-Kitab. Allah challenges all mankind to bring one chapter like it, if they doubt that it is the Word of God.
2:23 وَإِن كُنتُمْ فِي رَيْبٍ مِّمَّا نَزَّلْنَا عَلَىٰ عَبْدِنَا فَأْتُوا بِسُورَةٍ مِّن مِّثْلِهِ وَادْعُوا شُهَدَاءَكُم مِّن دُونِ اللَّهِ إِن كُنتُمْ صَادِقِينَ
And if you are in doubt as to what We have revealed to Our servant, then come with a Surah/Chapter like it; and call your witnesses besides Allah if you are truthful.
Linguistically, this book is a literal marvel for all times. No other book in Arabic has attained such linguistic magnificence as Al-Kitab. Nor the challenge in Al-Kitab to bring forth a chapter like it, has been met. The Arabic Grammar rules are derived from Al-Kitab and not vice versa.
5. This book piques the interest of even its opponent who think its false but cannot stay away from it and keep on doing their research in it, however, God increases them in disbelief with their efforts.
2:26 إِنَّ اللَّهَ لَا يَسْتَحْيِي أَن يَضْرِبَ مَثَلًا مَّا بَعُوضَةً فَمَا فَوْقَهَا ۚ فَأَمَّا الَّذِينَ آمَنُوا فَيَعْلَمُونَ أَنَّهُ الْحَقُّ مِن رَّبِّهِمْ ۖ وَأَمَّا الَّذِينَ كَفَرُوا فَيَقُولُونَ مَاذَا أَرَادَ اللَّهُ بِهَٰذَا مَثَلًا ۘ يُضِلُّ بِهِ كَثِيرًا وَيَهْدِي بِهِ كَثِيرًا ۚ وَمَا يُضِلُّ بِهِ إِلَّا الْفَاسِقِينَ
Allah does not shy away from citing the example of a mosquito, or anything above it. As for those who believe, they know that it is the truth from their Lord. As for the rejecters, they Say: What does Allah intend with this example? He lets many stray by it, and He guides many, but He only lets stray the Fasiqeen/evil-doers.
40:34 وَلَقَدْ جَاءَكُمْ يُوسُفُ مِن قَبْلُ بِالْبَيِّنَاتِ فَمَا زِلْتُمْ فِي شَكٍّ مِّمَّا جَاءَكُم بِهِ ۖ حَتَّىٰ إِذَا هَلَكَ قُلْتُمْ لَن يَبْعَثَ اللَّهُ مِن بَعْدِهِ رَسُولًا ۚ كَذَٰلِكَ يُضِلُّ اللَّهُ مَنْ هُوَ مُسْرِفٌ مُّرْتَابٌ
And to you there came Joseph earlier, with clear Signs, but you ever remained in doubt for what he had come for. Till when he died, you said. ‘No messenger will Allah send after him.’ Thus does Allah leave to stray who transgresses and lives in doubt.
4:82 أَفَلَا يَتَدَبَّرُونَ الْقُرْآنَ ۚ وَلَوْ كَانَ مِنْ عِندِ غَيْرِ اللَّهِ لَوَجَدُوا فِيهِ اخْتِلَافًا كَثِيرًا
Do they not consider/ponder The Quran/The Reading if it had been from other than Allah, they would surely have found therein much discrepancy/contradictions.
The True sprit of an Ayat of Al-Quran will be that which doesnot conflct with the understanding/sprit of other Ayas. So, if an understanding of an Ayat doesnot match with the understanding of other Ayas, it would mean there is a problem in understanding of that Ayat and more research is required in its understanding until the understanding harmonizes with the Spirit of other Ayas of Al-Quran.
The other supposedly heavenly books have problems with scientific discoveries and they cannot cope with them. However, with Al-Kitab as more information is known about the Universe and Earth, it is to be found that the information is congruent with the facts mentioned in Al-Kitab.