Attempting to find an answer to this question, Taseer sets off on a personal pilgrimage through the Islamic world. Starting in the fiercely secular Turkey, where many Islamic religious practices are forbidden by law, he makes his way slowly to Pakistan via Syria, Saudi Arabia - where he travels to Mecca - and finally the nominally Islamic state of Iran. Through conversations with various people, and his observations of life in each country, it becomes clear that there is no set answer. In Turkey he meets young men who dream about a world where everyone is ruled by Islam because it is the only faith which can tell you how to live properly. In Syria he sees how that dream is being actualized by a regime with its own political agenda and not above cynically manipulating people.
By offering people a version of the world free of all contradictions and questions, a world in which there is only one "truth," they can control them with the help of a compliant clergy. In Abu Nour, a centre for international students in Damascus, people come from all over the world to learn Arabic and take classes in Islamic studies. However sermons in the mosque include distorted views of history designed to depict Muslims as being persecuted throughout the ages and work up antagonism against an enemy simply referred to as the West. The result is the creation of a world that exists in isolation designed to equate being Islamic as a supporter of the Syrian government and any who oppose Syria are enemies of Islam.
When the book shifts to Iran the depiction Taseer offers is no different than any other description you've read of people living under any totalitarian regime. Here he finds that Islam is being used to harass people over trivialities, like the length of their shirt sleeves, in order for an insecure government to exert control over them. In fact in what is supposedly an Islamic republic where you'd expect to be able to find answers as to what is a Muslim, there is even less chance of discovering that here than anywhere else. For, as a university professor he meets puts it, "People were very connected to religion even though the government was not religious. But now the government is religious most people want to get away from religion... It is very hard for me to say I am a Muslim."