Okay, what I don't understand is that why is there so many version of the bible. If you were to ask two random Christians from the world to recite something from the bible from a certain section, surely they cannot recite the same exact thing. Yet you ask two random Muslim people to recite the Quran they will recite the exact same thing because there is only one version of the Quran therefore it is unlikely for the Quran to have changed. The Bible has so many version that the original version is completely different.

Another point, the reason why I believe that God has sent down the Quran is because there is absolutely no proof of Muhammed having the ability to write the Quran. He was never able to read or write Arabic. He grew up in the countryside where there was no formal education of how to read and write Arabic. Even when the people of Makkah came in agreement with a sheet, they were shocked that he could not read the agreement sheet.

The thing about Muslims is that we believe in the Original bible but it's been changed so many times that God sent down the Quran which is the final and last book sent down. That is why there is no more prophets for the last 1400 years.