"I think, Rev. Barber, of all the contemporary leaders, comes closest to that kind of passion and deep sense of spiritual awareness of the problems of our society. It's almost like [King] is whispering in Rev. Barber's ear," Carson said.

Those are big words, but Barber delivered at Stanford’s Memorial Church Thursday night.

Barber limped to the podium with a knee injury sustained, he said, during a recent arrest in Washington DC. He also struggles with a medical condition that affects his mobility, but the overall effect of watching this former football player struggle to his feet elicits a rush of sympathy and concern from his audiences around the country when he rises to speak. It's something you don't see when you see him on television, seated on a panel on MSNBC or Real Time With Bill Maher.

The capacity crowd of 1,500 rose to greet him with a standing ovation. Half the people in the pews looked old enough to have marched with Dr. King. Half looked just old enough to vote.

The pastor began by arguing against indulging in nostalgia for the glory days of the civil rights movement. "I'm humbled to stand before you as we honor the legacy of Rev. Dr. Martin Luther King, and I will tell you, I don't do King celebrations. Because I think we're at a point where we do not need to celebrate as much as we need to engage."

Then he went on to say, "To truly honor a martyr, we must go where they fell, pick up their baton, and carry it the rest the way."

Like Dr. King, Barber challenges his audiences to do something about systemic racism, poverty, the war economy and other injustices.

Like Dr. King, Barber employs many of the same political tools: marches, civil disobedience and voter registration drives. In recent years, he co-founded the Poor People’s Campaign: A National Call for Moral Revival, a revival of the original launched by King and the Southern Christian Leadership Conference.

Barber is firmly in the Democrats' camp, and beyond that, the progressive wing of it, but he rhetorically insists on a bi-partisan, historically rooted understanding of American politics, urging liberals to move past their current, obsessive hatred of President Donald Trump.

"Let me say Trump is not America's biggest problem. Oh, I knew y'all wasn't going to clap. That's alright. Trump is a symptom!"

Barber diagnoses instead a "spiritual and moral sickness that has not been cleansed from the veins of this democracy still produces moral emergency we are facing as a democracy."

"America needs more than a new president. We need a new moral revolution of values," he said, raising one eyebrow.

Barber has developed a reputation for his King-like ability to blend politics and theology in his speeches without it feeling forced, and he invoked King's last speech in Memphis to argue for practical action.

"True preaching cannot rest on a page, sit in a song, or travel on a tweet alone. Absolutely nothing would be more tragic than for us to turn back now. It’s movement time," he roared as the crowd rose to its feet.

Those introducing him and Barber himself warned he was on a tight schedule. He would not be able to stay after the speech and personally respond to 1,500 people keen to shake his hand.

As he left the stage, presumably headed straight to the airport, the iconic local folk singer Joan Baez joined an a cappella group of Stanford student singers, Talisman, to sing an old civil rights standard, 500 Miles.