How does king defend his philosophy of nonviolence against the claim that it is cowardly or passive?

Answer:

He defends his belief in nonviolence and civil disobedience by stating that it is much more efficient to defeat an enemy through friendship than through violence and harm.

Explanation:

Martin Luther King Jr., the most famous of African American activists in the United States, and through whose efforts the movement for civil rights saw a great improvement, was not initially a believer in pacific protest and nonviolence. Initially, he was a believer of self-defense and even kept guns in his home, in case there was an attack. However, through the influence of people very close to him, pacifists Bayard Rustin, Harris Wofford and Glen Smiley, who led him to learn about Mahatma Ghandi and his own civil disobedience movement in India, and also read Henry David Thoreau´s work on civil disobedience, Martin Luther King saw a change in his way of thinking. Also, his contact with the Christian movements, he came to realize that throughout history, Christianity had opposed corrupt and evil governments and systems through a very succesful friendly, and non-violent, system of opposition, which had changed history several times. These were all reasons why Martin Luther King Jr., later became a great advocate of the nonviolence and civil disobedience system, instead of violent acts.

King believes that non-violence is not weak because although physically they do not react but spiritually they are firm in their beliefs and are determine to effect change.  It takes a lot of courage to march amidst a hostile crowd and be beaten and hosed down.  A coward would not last long under those conditions but they did.