It was a stunner, unexpected by the millions who were watching -- and probably by most of those in the chapel that day!
which lasted all of 14 minutes, brought us back to what matters as Christians, the idea that the essential teaching of Jesus has the power to transform the world.
They represent the future of Christian thinking, envisioning a time when we put aside petty hatreds, when we stop thinking about refugees as enemies, when we embrace our friends at home and abroad as neighbors grounded in the love of God, which only becomes visible when we act in a loving manner, treating our neighbors as we ourselves would like to be treated.
He began with the most famous poem of earthly love in the Bible, the Song of Solomon, then shifted rapidly to quote Martin Luther King: "We must discover the power of love, the redemptive power of love. And when we do that, we will make of this old world a new world, for love -- love is the only way."
Just to bring in Dr. King in this context was a fresh wind in Windsor Castle: King is the prime example of a man who showed the world what love multiplied by millions of marching men and women could do, as in the civil rights movement, which helped to bring an end to the Jim Crow era, when black people had to sit at the back of the bus and could not sleep in the same motel as white people or sit beside them in a diner.
It's not that racism was banished after the Civil Rights Act of 1964. We're subjected every day to forms of hate speech, from the White House on down. A very long road to freedom still lies before us, and it will be many years before we can honestly say that America is a place where it's obvious that all men and women were created equal.
But that's the dream.
Bishop Curry held this dream before us, a dream grounded in God's love: "There's power in love," he said. "Don't underestimate it."
He didn't hold back, as Dr. King -- with his immense freedom of thought -- never held back: "There's power in love to lift up and liberate when nothing else will."
Curry then said: "If you don't believe me, well, there were some old slaves in America's antebellum South who explained the dynamic power of love and why it has the power to transform. They explained it this way. They sang a spiritual, even in the midst of their captivity. It's one that says, 'There is a balm in Gilead...' a healing balm, something that can make things right.'"
You couldn't easily miss the significance of the moment -- an African-American preacher evoking slavery to the British royal family, whose colonial-minded forebears not so long ago enslaved millions around the globe.
Wisely, Curry didn't dwell on this unhappy history. He looked to the future, asking us to imagine a world where "love is the way," even in business and commerce. He invited us to imagine neighborhoods and communities bathed in love, not mutual suspicion, not fear of the other.
In the world he imagines, "poverty will become history." He asked us to think what it would be like to live in a world where no child would go to bed hungry.
Again, without naming him, he invoked the sweeping rhetoric of King: "When love is the way, we will let justice roll down like a mighty stream and righteousness like an ever-flowing brook."
And he wasn't done. He went on to envision a world where nations would lay down their "swords and their shields" and people would "study war no more."
He asked us to think about a time when we treat everyone in the world as family. As brothers and sisters in God.
In closing, Curry summoned the Catholic priest, scientist and mystic Teilhard de Chardin, who regarded fire as the first great discovery, one that led to everything from the heating of homes to modern technological wonders, such as the "controlled fire" that allowed Curry himself to cross to Atlantic by jet to attend this wedding.
Teilhard said that if humanity could harness the power of love, this would be the "second time in history that we discovered fire."
Curry ended his brilliant sermon as he began, with Dr. King, who said we must rediscover the redemptive power of love, and use this power to remake the world.
We should be thanking Bishop Curry, for his beautiful and moving words.
This is the Christianity that will change the world, one that offers a positive vision, moving beyond dark visions of end times In Jerusalem, beyond a fear and loathing of those who do not seem like us.
Curry -- not unlike Pope Francis -- holds before us a vision of Christ's message that young people can embrace, a vision of boundless love, with a passion for social and economic justice that will carry us forward into a new world.