Martin Luther King, Jr.'s (1929—1968) birthday was January 15, 1929 and he would have been 86 years old, if he had lived until today. MLK was assassinated on Thursday, April 4, 1968 when he was 39 years old in the Lorraine Motel in Memphis, Tennessee.
Tomorrow is the only major federal holiday in the United States named after a historical person, Martin Luther King, Jr. Day that celebrates MLK's birthday, observed on the third Monday of January.
In the following quotation by James H. Cone in Risks of Faith: the Emergence of a Black Theology of Liberation, 1968-1998, he argues that Martin Luther King, Jr. is America's Most Outstanding Theologian. Evangelicals attribute this honorary title to Jonathan Edwards, but Edwards was forgotten for two hundred years until Perry Miller rediscovered him and the other American Puritans—yet the question remains, how may the greatest theologian in America be forgotten for centuries in country formed in 1776? Maybe the Niebuhr brothers (whom James Cone adores) could be a named as the "Greatest American Theologian", but as popular as they may be, or as genius their books may have been, their work's influence on America's civil and social structure pale by comparison to Martin Luther King, Jr. And, I would argue that those Evangelicals that would nominate Jonathan Edwards today, are more often than not, have never heard of Reinhold Niebuhr and H. Richard Niebuhr.
When Americans celebrate Martin Luther King, Jr.'s birthday as a national holiday, seminary students and faculty, church leaders and Christians throughout the world should not forget his importance as theologian, perhaps the most important in American history. In saying this, I do not wish to minimize the significant contribution of other theologians—whether Jonathan Edwards, Walter Rauschenbusch, or the Niebuhr brothers. There are three reasons that make Martin King a candidate for the status of America's most outstanding theologians:
1. If theology is a disciplined endeavor to interpret the meaning of the gospel for the present time, and if the gospel is God's liberation of the poor from bondage, then I would claim that no one has articulated the Christian message of freedom more effectively, prophetically, and creatively in America than Martin Luther King, Jr.
2. Unlike many American theologians who often look toward Europe to identify theological problems that require disciplined reflection, Martin King's theological perspective achieved its creativity by engaging uniquely American issues. He was truly an American theologian and not simply a theologian who happened to live in the United States. No theologian has made a greater impact on American culture than Martin Luther King, Jr. Making his birthday a national holiday merely symbolized that fact.
3. Unlike most white theologians who do theology as if their definitions of it are the only ones and as if their problems are the only ones that deserve the attention of disciplined theological reflection, Martin King did not limit his theological reflections to the problems of one group. While he began with a focus on the racial oppression of blacks, his theological vision was universal. He was as concerned about the liberation of whites from their oppression as oppressors as he was in eliminating the racial oppression of blacks. He was as concerned about the life-chances of brown children in Vietnam as he was about black children in America's cities. King's vision was truly international, embracing all humanity. That is why his name is invoked by the oppressed around the world who are fighting for freedom. Teachers of theology do themselves, their students, and their discipline a great disservice when they ignore the outstanding contribution that King has made to American theology and to all who are seeking to understand the gospel today. For if one wishes to know what it means to be a theologian, there isn better example than Martin Luther King, Jr. 
1. Cone, James H. Risks of Faith: the Emergence of a Black Theology of Liberation, 1968-1998. Boston, MA: Beacon, 1999. 72-3. Print.
Header: Karl Barth with Martin Luther King, Princeton, 1962 (source: kbarth.org)
Related: 1968-1998, H. Richard Niebuhr, James Cone, James H. Cone, Jonathan Edwards, Martin Luther King Jr., MLK, Perry Miller, Reinhold Niebuhr, Risks of Faith: the Emergence of a Black Theology of Liberation, Walter Rauschenbusch