If anyone had a right to unleash an uncivil, scathing … attack on his opponents, it was Dr. Martin Luther King Jr. It is hard for [many people today] to remember the conditions under which many African Americans lived throughout the South just over 40 years ago. Segregation, lynchings, African American churches and homes firebombed. Jim Crow laws even prevented "colored people" from attending the circus and playing pool with whites.

Yet civil rights leaders painfully, persistently, and peacefully protested the injustice of segregation. In doing so, they often broke segregation laws. All too often, protesters reaped a reward of fire hoses, police dogs, and incarceration.

Several Birmingham clergy admonished the protesters, urging them to work within the law. King's letter was a response to those clergy.

Put yourself in his place. Who would not be furious, even enraged, by the statement of these ministers? How was King able to respond in such a civil and well-reasoned manner? Remember that King himself was a Baptist pastor. His response—known today as the "Letter from Birmingham Jail"—reflected his deeply held Christian convictions. He quoted the words of Jesus, and appealed to the example of Paul, as well as Thomas Aquinas, Martin Luther, and John Bunyan.

Also, he did not question his opponents' motives. Instead, he called them "men of genuine good will" whose "criticisms are sincerely set forth." "I want to try to answer your statement," he wrote, "in what I hope will be patient and reasonable terms." And that he did.

Yes, King clearly cataloged the injustices faced by African Americans. He called "white moderates" to task and forcefully reminded them that justice delayed was justice denied. And most famously, citing Augustine, he claimed that "an unjust law is no law at all."

But King never engaged in name calling or personal attacks. Without distortion, he patiently and fairly acknowledged his opponents' positions—and then dismantled them.

King had reason, justice, facts, and conviction on his side—as well as the gospel. He did not need vitriol, and he did not employ it.

Our country is grappling with many high-stakes, emotionally charged issues….We should defend our positions vigorously and with conviction—but with civility. That is why our nation more than ever needs the spirit contained in King's "Letter from Birmingham Jail."