Why the Long Arc of the Moral Universe Still Bends Toward Justice

Today the nation marks the Rev. Martin Luther King, Jr. holiday. For some federal and state workers, this means a day off. For many on social media, it means a cue to virtue signal by trotting out a well-known MLK quote. A couple of snippets from the well known, “I Have a Dream” speech will get the most use.

Few Americans outside of academic circles have ever read King at length. We know him almost exclusively in pithy quotes and grainy, black-and-white sound bites. But he was a brilliant, eloquent, persuasive writer. His best-known speeches are really just extensions of his genius as a writer.

His “Letter from Birmingham Jail” is a stunning tour-de-force apologetic for the Civil Rights Movement in the tradition of the great Christian apologists of the second and third centuries. In it, he builds a case, addresses common objections, and appeals to the better angels of the readers’ natures. A taste:

I am cognizant of the interrelatedness of all communities and states. I cannot sit idly by in Atlanta and not be concerned about what happens in Birmingham. Injustice anywhere is a threat to justice everywhere. We are caught in an inescapable network of mutuality, tied in a single garment of destiny. 

Poetry. In “Birmingham Jail” King reminds me of the early church father Tertullian of North Africa, who wrote repeatedly to the the Roman authorities pleading the case of the oppressed, persecuted, and scapegoated Christians of the Roman Empire. Tertullian famously warned the Romans:

The more we are mown down by you, the more in number we grow; The blood of the martyrs is the seed of the Church.

One of Rev. King’s most oft-quoted phrases is some variation of: “The arc of the moral universe is long, but it bends toward justice.” (It is sometimes quoted as “the arc of History . . .”) King used this phrase in a 1958 article called “Out of the Long Night” published in The Gospel Messenger—the official publication of The Church of the Brethren.

This quote did not originate with King. In fact, he put the phrase in quote marks in the article to indicate that he was citing a saying that he assumed was already known to the reader. King later repeated the phrase is several speeches. The originator of the saying was a Unitarian abolitionist minister named Theodore Parker, born in 1810.

Rev. Theodore Parker (1810-1860)

What MLK quoted was a boiled down version of what Rev. Parker originally wrote:

Look at the facts of the world. You see a continual and progressive triumph of the right. I do not pretend to understand the moral universe, the arc is a long one, my eye reaches but little ways. I cannot calculate the curve and complete the figure by the experience of sight; I can divine it by conscience. But from what I see I am sure it bends towards justice.


In both forms, the message rings as true. Doubly so if you’re a student of History. But why? Why has the story of the last 2000 years been one of gradual but consistent upward progress, particular in the West?

The answer, of course, is Christianity . . . or more accurately . . . the presence of the kingdom of God on earth, expanding, unfolding, leavening the cultures of the world like yeast.

The abolition of slavery; the elevation of the status of women in society; respect for private property and the rights of the individual; and the gradual dissolution of class distinctions are all the emerging expressions of the Christ’s emerging kingdom.

It’s tempting and far too easy to focus on what remains to be done. But the kingdom cotinues to expand. The arc still bends toward justice.