King’s letter is one of the many often ignored treasures in American liberal democracy and in the application of Christian moral theology to public life. These are a few shorter quotes, but it’s worth reading the whole thing, since some of the best passages are just too long to reproduce here. (Underlines have been added.)

I cannot sit idly by in Atlanta and not be concerned about what happens in Birmingham. Injustice anywhere is a threat to justice everywhere. (p264)

… I am not afraid of the word tension. I have earnestly worked and preached against violent tension, but there is a type of constructive nonviolent tension that is necessary for growth. (p266)

… we must see the need of having nonviolent gadflies to create the kind of tension in society that will help men rise … (p266)

… as Reinhold Niebuhr has reminded us, groups are more immoral than individuals. (p267)

… one has a moral responsibility to disobey unjust laws. I would agree with Augustine that “An unjust law is no law at all.” (p268)

Of course there is nothing new about this kind of civil disobedience. It was seen sublimely in the refusal of Shadrach, Meshach, and Abednego to obey the laws of Nebuchadnezzar because a higher moral law was involved. It was practiced superbly by the early Christians who were willing to face hungry lions … (p269)

… it is immoral to urge an individual to withdraw his efforts to gain his basic constitutional rights because the quest precipitates violence. Society must protect the robbed and punish the robber. (p271)

a tragic misconception of time. It is the strangely irrational notion that there is something in the very flow of time that will inevitably cure all ills. Actually time is neutral. It can be used either destructively or constructively. (p271)

So the question is not whether we will be extremist but what kind of extremist will we be. Will we be extremists for hate or will we be extremists for love? Will we be extremists for the preservation of injustice — or will we be extremists for the cause of justice? …. So, after all, maybe the South, the nation, and the world are in dire need of creative extremists. (p273)

I have been so greatly disappointed with the white Church and its leadership.(p274)

I have wept over the church. But be assured that my tears have been tears of love. There can be no deep disappointment where there is not deep love. (p275)

I am meeting young people every day whose disappointemnt with the Church has risen to outright disgust. (p276)

I have consistently preached that nonviolence demands that the means we use must be as pure as the ends we seek. So I have tried to make it clear that it is wrong to use immoral means to attain moral ends. But now I must affirm that it is just as wrong, or even more so, to use moral means to preserve immoral ends. (p278)

… when these disinherited children of God sat down at lunch counters they were in reality standing up for the best in the American dream and the most sacred values in our Judeo-Christian heritage, and thus carrying our whole nation back to great wells of democracy … (p278)

*[These are from the “first version” as reproduced in The Best American Essays of the Century, ed. Joyce Carol Oates & Robert Atwan, Houghton Mifflin, 2000, p263ff. The “second version” is available in King’s Why We Can’t Wait.]