In order to make sense of this book, one should view Martin Luther King, Jr's version of Christianity, because he was a minister, and this entire book is literally predicated on a Biblical metaphor. The metaphor is that the black communities were like the Israelites in Egypt who, upon earning their freedom from slavery, had to walk through the desert before they could attain peace. For the Israelites, peace was Israel itself, a land where the ancient Hebrew people could establish a kingdom. For King, paradise was nonviolence and racial harmony.
King views Rosa Parks as a kind of martyr for the cause, because she was publicly hated by racists, and she became an object metaphor for the problems of racism, but that is also the inciting incident that helped King to gather public attention to the problem of racism and segregation. Rosa Park's suffering catalyzed an entire movement across the nation where black communities rallied for racial harmony, without rioting, peacefully. Therefore, it could be argued that in a nonreligious way, she actually is literally a martyr for the cause of peace and harmony.
This brings us to the issue of nonviolent demonstration. Only a few decades before the events of the Montgomery Bus Boycott, Gandhi had successfully bypassed a revolutionary war in India by perfecting the art of nonviolent political demonstration. Therefore, King knew the technique, so he simply implemented it as it had been done there, and when he combined his religious intuition, his sense for what Christ actually stands for (freedom and love), and the real events of Rosa Parks's life, he literally did change the world.
