I think that the Koran makes the case for itself as an immortal work as most others make the case. It is a work that is seen as the words from the divine, providing revelation and meaning to the mortal in search of truth. Muhammad was the divine messenger that transmits the word of the divine through the Koran to the world of the mortal. Its case is made as a work of the immortals because it stresses that the words that the Prophet Muhammad writes represents "God's word." It is in this that the Koran is taken as being representative of the Islamic faith, and immortal in its own right. I think that this is where its case is made. There is no other work in the Islamic religion that has such a close relationship or proximity to the divine than the Koran. It is here where worship in the faith starts, another reason for how the book's case for immortal, the actual words of the divine, is demonstrated. If nothing else, consider the reaction in the Muslim world to the burning of Koran texts on a military base in Afghanistan. I think that the reaction of Muslims across the world could also be used as evidence that clearly suggests that the Koran's value is seen as an immortal work, the actual words of the divine being transmitted to the mortal. In such a visceral and intense reaction, its case is proven.