Themes are the fundamental and often universal ideas explored in a literary work. 

Learning History’s Lessons  

Various kinds of history are included in “Letter from Birmingham Jail,” and King draws on all of them to support his argument against racial inequality. Most important is the history and legacy of enslavement. King points back 340 years, to the early colonial period when the first Black American was born, and argues that it is long past time that the United States lives up to its ideals by treating all citizens fairly and equally. References to specific Americans, like John Bunyan and Abraham Lincoln, make clear that it is possible to enact change. Recent world history, like the examples of the Third Reich and the Soviet Union, help to establish the various forms that inequality can take. Events from the Bible, such as King’s references to the Book of Daniel or the Gospel of Matthew, also provide evidence for the argument King makes. 

Intellectual and literary history are also crucial to how King crafts his argument. Rather than examining what people did, these kinds of history look at what they wrote and thought. References to important thinkers, from St. Augustine to Reinhold Niebuhr, locate the letter in a long intellectual tradition and offer an implicit defense of King’s ideas to skeptics or critics, people who might doubt he lacks the authority to make his claims. Finally, King’s deft use of literary tradition, both the history of sermon writing and the rhetoric of protest writing, lends power to the way he presents his ideas. Across the work, it is clear that King has studied history carefully and learned from its many lessons. The “Letter from Birmingham Jail” challenges readers to do the same and to acknowledge that on the basis of history, Black Americans must be granted the freedoms to which they are justly entitled. 

Defining Justice 

In “Letter from Birmingham Jail”, Martin Luther King joins the countless philosophers who have tried to provide a definition for the concept of justice. At first glance, the answer might seem simple. However, as these countless philosophers discovered, it is actually very hard to be precise about justice, even though most people have a rough idea of what it means—treating people fairly. King’s contribution to this debate is useful in several ways. First, he is very clear about the two main ways that justice is used: with reference to legal systems, which render justice for societies, and in terms of morality, which teaches us how we should treat others. As King shows across his letter, these two senses of justice can conflict, which is one of the reasons that the concept is difficult to define. King not only differentiates these two meanings of the word, but he also argues that the moral meaning of justice must be understood as the more important of the two, for it concerns what is right and wrong and not merely what is legal or illegal. Equality is the principle that King relies on to make his understanding of justice clear. Pointing to several examples, he indicates that systems that make inequality necessary are inconsistent with the idea of justice. Although he does not think that all people are the same, King insists that any system which values justice over injustice should treat people according to standards that apply equally to all. 

The Obligations of Faith 

King is explicit in “Letter from Birmingham Jail” that religious faith has social obligations. While he never denies the more private dimensions of belief, he is explicit that any religion practice that focuses narrowly on the individual, that is divorced from the larger community, is misguided for it has lost its mission and its way. King communicates this message in multiple ways in his letter. He stresses the role of self-purification as a part of nonviolent direct action. Everyone who participates much examine his or her motives, purging those that are inconsistent with the campaign’s spiritual aims. King also argues that the white church has lost its influence because it values conformity over justice. When he recalls the original idea of congregation, through the word "ekklesia," King suggests that any true religious assembly should be inclusive, not segregated or exclusive. As he celebrates the spiritual balm he takes from the work of white allies, King establishes that faith has many sources and forms of expression, but they must all embrace the gospel as a force of social justice.