The actual quote by the late Reverend Martin Luther King, Jr., is as follows:
"A man dies when he refuses to stand up for that which is right. A man dies when he refuses to stand up for justice. A man dies when he refuses to take a stand for that which is true."
The origins of the oft-cited quote included in the student's question is uncertain, as it was attributed to King by somebody else. Be that as it may, King's March 8, 1965, speech in Selma, Alabama, in which he made the above statement, stands as a touching expansion upon 18th century English philosopher Sir Edmund Burke's famous observation that "the only thing necessary for the triumph of evil is for good men to do nothing." King's point, as with Burke, was that evil or injustice left unopposed will invariably prevail over justice, with unfortunate consequences for the whole of society. Those who recognize that a wrong is being committed and who fail to act may not be culpable with the triumph of evil, but neither are they innocent of the bad that results. King, as his religious education and training suggest, believed in the existence of a soul, and man's soul would not survive the failure to act in the face of injustice. Speaking in the context of the centuries-old struggle for civil rights, King's words constituted yet another clarion call for all people to stand up for what they know is right.
Martin Luther King, Jr. is best known for his work in the civil rights of African-Americans. He is probably the best known figure in the fight for social change in this country. He was also a minister, and considered this his true calling. He preached the gospel, but he also lived it. He was passionate about the plight against the black community during the 50's and 60's.
When he made this statement he was talking about how, for way too long, people of all colors kept silent to the injustices being done. He knew that most people were scared of being killed if they spoke up and tried to do something. Most of the authority figures in the south were corrupt and would physically harm people who tried to fight against the things being done. Dr. King was trying to get more people involved in the movement. He knew that if we as a society keep silent and do absolutely nothing about unfair treatment these people were experiencing, that a part of our soul would die. He knew that the only way to make a difference is to do something. Yes, it was scary, yes some people's lives were in danger and yes some people even died, but they did something. These people paved the way for the liberties that we can now appreciate. We have a long way still to go, but we have to stop being silent and rise up and do something. Dr. King was all about peaceful resolutions, and we need to get back to what Dr. King taught all of us.
Martin Luther King, Jr. is, of course, best known as a man who worked to end injustice in the United States. The quote that you have given here shows how important he it is to fight against things that are unjust. King is saying that we are not truly alive unless we speak out for justice. If there are things that matter, things like injustice, we have to speak out rather than being silent. Otherwise, we are sort of giving up our humanity and, thus, ending our lives not in a physical sense but in a figurative sense.