If President Obama tries to mark the 50th anniversary of the civil rights March on Washington this week by repeating Martin Luther King Jr.’s “I Have a Dream” speech on federal property, don’t be surprised to see the church-state-separation types squawking in protest.

I’m mostly kidding, but there’s a serious point. The speech King delivered on August 28, 1963, contains religious language that might well strike some contemporary listeners as a violation of the more expansive definitions of the First Amendment’s Establishment Clause.

Three times, after all, the great speech makes reference to “all of God’s children.”

There’s no mention of those who don’t believe in God.

The concluding paragraph makes reference to that day when “Jews and Gentiles, Protestants and Catholics” will be able to sing “Free at last, Great God a-mighty, We are free at last.”

Again, no reference to atheists or non-believers. No reference to Muslims or to adherents to Hinduism. No mention of those who think God is not almighty.

Five times the speech speaks of faith. King urged listeners, “Continue to work with the faith that unearned suffering is redemptive.”

That faith is particular to Christianity; for other religions, “unearned suffering” is not necessarily redemptive but can instead be something that either poses theological problems or is to be avoided ardently.

In King’s “dream,” “the glory of the Lord shall be revealed,” and we will be able “to pray together.”

If you aren’t interested in praying, or in having the Lord’s glory revealed to you, you may nonetheless be able to share the parts of King’s dream that involve racial integration, freedom, and equality under the law. But the rest of King’s dream you may find remote. That is significant, because the theological language and the ideology behind it provides the philosophical and emotional underpinnings for the rest.

King was an ordained Baptist minister. His father, Martin Luther King, Sr., was a minister. So was King Jr.’s maternal grandfather, the Reverend Adam Daniel Williams, according to a biographical sketch at the Louisiana State University Library.

It’s one thing for a civil rights leader to speak like this, even on government property; it would be another thing for the president to say the same words. People’s reactions to the language will depend on their own religious views, or lack of them.

Strictly as a matter of historical fact, though, as America and President Obama mark the 50th anniversary of the march, it would be a mistake to understand King, or the march, or the civil rights movement as a whole, as being limited conceptually to a legal definition of racial freedom, such as getting a Civil Rights bill passed, or to an economic definition, such as having black employment and income statistics reach parity with those of the rest of the U.S. population.

Rather, they were animated by a moral vision that King quoted in his speech, the one from the Declaration of Independence — “that all men are created equal.”

This concept of natural or God-given rights influenced and motivated the founders in the American Revolution, the abolitionists in the Civil War, the anti-Fascists in World War II, and the anti-Communists in the Cold War.

As a guide for policymaking, it can be problematic, because God’s present reluctance to adjudicate disputes over which rights are God-given and which are not leaves a lot for us humans to figure out for ourselves. But as a basis for inspiring the expansion of freedom, it’s hard to beat. If President Obama can make that point in his anniversary remarks, they will be a success. And if not, the religious underpinnings of the “I Have a Dream” speech are one important reason that future presidents will be marking the anniversary for many generations to come.

Mr. Stoll is editor of FutureOfCapitalism.com and of Smartertimes.com.