What is the main conflict in Muhammad: A Biography of the Prophet by Karen Armstrong?

Muhammad, A Biography of the Prophet, by Karen Armstrong, tells the story of the Prophet Muhammad and how the religion of Islam came into existence. At this time, Christianity and Judaism had developed and had a form of written scripture. The Arabs, who were still basically a tribal nomadic society, did not have any written scripture which bothered them. This is what the Prophet Muhammad provided them with even through he was illiterate.