Fifty years ago this week, a quarter of a million Americans converged on the nation's capital in the largest and most important civil rights demonstration in American history: the March on Washington for Jobs and Freedom.

It was a humid summer day on the national mall, and the Rev. Martin Luther King Jr. was the last of nine speakers. The mood was jubilant but tense, with combat troops poised to intervene in case of violence.

King read from a prepared text, invoking the Declaration of Independence, the Constitution and the Bible to call America to repentance for its unequal treatment of its black citizens. People fanned themselves and some milled about.

Then King put his text aside, sensing, he would later say, something in the audience. Gazing out over the crowd, he began to improvise.

"I still have a dream," he boomed. "It is a dream deeply rooted in the American dream."

Even on video, even 50 years later, the moment is electric.

"I have a dream that one day on the red hills of Georgia the sons of former slaves and the sons of former slave owners will be able to sit down together at the table of brotherhood. …

"I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin, but by the content of their character. I have a dream today."

It was a set-piece — a rhetorical building block often used by black preachers to focus the audience and advance the sermon — and it wasn't the first time he had used it. It was also what is known as an anaphora, or phrase repeated for emphasis and emotion. (King used several in his speech, including "now is the time" and "free at last."

But more than that, it was a neat example of the fact that what made King so effective was precisely his background as a preacher — not a lawyer.

The importance of King's deep faith, and that of his followers, is at times overlooked in historical retrospectives on his legacy. But, as reporter Matthew Brown details in today's Deseret News, religion was a compelling source of vision and motivation for black and white civil rights protesters alike.

It was more than his ability to deliver a stirring sermon that gave King his moral authority (the organizer of the march, A. Philip Randolph, introduced him that day as "the moral leader of our nation"). For many, King spoke with inspired authority, his words coming "from some higher place," as his wife later said of his speech at the march. As he looked into the distance, they could believe he really was seeing in vision the dream of which he spoke.

Religion wasn't simply an organizing tool for King; it was his driving force.

For many, especially our youth, today's religious institutions appear to be fossilized and irrelevant organizations that default to the letter of rules and restrictions instead of the spirit of compassion. But the deeper truth is that religion remains an indispensable force for organizing around society's most pressing moral issues, as well as a scaffold for accessing life's deepest spiritual motivations and experiences. Indeed, some of the most powerful voices opposing modern-day slavery and pushing for humane immigration reform are coming directly from our nation's houses of worship.

Religion has the power to inspire. There is nothing quite so powerful as a man or woman speaking from the depth of the soul, with vision of a brighter day, tapping into the longing of the human heart for a more just, more peaceful, more righteous world.

King didn't just decry injustice — though he most certainly did do that. He also painted a vision of a bright future.

"With this faith," he said, employing another repeated phrase, "we will be able to hew out of the mountain of despair a stone of hope.

"With this faith, we will be able to transform the jangling discords of our nation into a beautiful symphony of brotherhood.

"With this faith, we will be able to work together, to pray together, to struggle together, to go to jail together, to stand up for freedom together, knowing that we will be free one day."

His words echo today, giving us pause to reflect on dreams partly fulfilled and calling us to make good on promises still unfulfilled. May we heed the call.

The 15 best quotes from Martin Luther King Jr.'s 'I Have a Dream' speech