While part of him loves the shrine and wants to fulfill his destiny as the anointed heir and future Saheb, Karsan also desires the learning and enticements offered by the material world. When he applies for admission to Harvard University in the United States it's not with any real hope of being accepted, or, even if that miracle were to happen, of being able to attend. But when the unthinkable occurs and Harvard offers him a full scholarship, including airfare, how can he turn it down?
He knows that if his father forbade him he would stay, and not even be too resentful, but he is allowed to choose for himself, in spite of his father's worst misgivings. He assures one and all that he will return to take up his duties when his schooling is done, and he is certain that spending time in the world beyond their village will enable him to serve the people with even greater wisdom.
India is also different than it was during Karsan's father's youth; for one thing it is now India and Pakistan, Muslim and Hindu, and that gap is too wide for the way of the Sufi to straddle in safety anymore. During the first Pakistan-India war it starts to become apparent to even Karsan that things aren't going to remain the same as they once were.
At their shrine, the family does not worship Allah, but their names are Muslim, and across the road from their shrine is another, a Muslim shrine, where the body of the Sufi's grandson is entombed and worshiped. For some, the conclusion is only too clear: if you are not one of us you are one of them. Yet for a time, peace is kept in the village, and the sanctity of the shrine is respected.
Karsan is determined to leave everything behind, including thoughts of the ugliness that lies beneath the glamor of India. He too is offered the temptation of worldliness over Godhood, and he steps across the line in reality and accepts the offer, completely turning his back on what he was supposed to have been.
The Assassin's Song is not based on the life of any real mystic, according to the author's note at the end of the book. It's rather an amalgamation of stories told about Muslim seers who came to India in the 11th and 12th centuries AD preaching a benevolent practice of worship based on neither the Muslim nor the Hindu faith, while freely recognizing both. Through this invention M. G. Vassanji has brought to life a world that very few of us in this age will recognize. In our ignorance we might call the prevailing attitude blind faith, and wonder about people today who still believe a person can be the avatar of a god.