Since the great human rights leader Nelson Mandela was born 100 years ago, the world has improved for billions of people. But on his centennial, global progress is at risk of stalling — and even reversing.

That was the primary theme of former US President Barack Obama’s historically sweeping and politically pointed speech Tuesday at the 16th annual Nelson Mandela Annual Lecture, sponsored in part by Global Citizen partner Motsepe Foundation, in Johannesburg, South Africa. He called on people around the world to promote democracy, fight inequality, empower young people, and recognize the common humanity that binds everyone together.

Take Action: Commit to Be the Generation to End Extreme Poverty

“On Madiba’s 100th birthday, we now stand at a crossroads," Obama said. "A moment in time at which two very different visions of humanity’s future compete for the hearts and the minds of citizens around the world. Two different stories, two different narratives about who we are and who we should be. How should we respond?”

The first story, Obama explained, believes that transparent and accountable democracies can ensure universal basic rights like access to education, health care, housing, food, water, and more. It’s a narrative that promotes acceptance and diversity and seeks to end inequalities.

The second story, ascendent in recent years, is a “politics of fear and resentment and retrenchment,” Obama said, “whereby elections and some pretense of democracy are maintained – the form of it – but those in power seek to undermine every institution or norm that gives democracy meaning."

Read More: 2017 Was Especially Dangerous for Female Journalists

Obama took the opportunity to slam political leaders who reject objective facts, stoke fear, enact racist immigration laws, and undermine democracy.

"You have to believe in facts," he said. "Without facts, there is no basis for cooperation. If I say this is a podium and you say this is an elephant, it’s going to be hard for us to cooperate."

During his speech, Obama sketched the political arc of the past century to make a case for open democracies, using Mandela as the throughline.

He came to embody the universal aspirations of dispossessed people around the world, their hopes for a better life, the possibility for a moral transformation in the conduct of human affairs.

"There was no reason to believe that a young black boy at this time, in this place, could in any way alter history," he added. "After all, South Africa was then less than a decade removed from full British control. Already, laws were being codified to implement racial segregation and subjugation, the network of laws that would be known as apartheid."

"Most of Africa, including my father’s homeland, was under colonial rule," Obama continued. "The dominant European powers, having ended a horrific world war just a few months after Madiba’s birth, viewed this continent and its people primarily as spoils in a contest for territory and abundant natural resources and cheap labor. And the inferiority of the black race, an indifference towards black culture and interests and aspirations, was a given."

Read More: 7 Ways Nelson Mandela's Legacy Still Resonates Today

Obama described how, a century ago, the majority of the world’s population lived in subsistence poverty, women were denied basic rights, and a person’s fate was largely determined by socioeconomic circumstances.

Decades of advocacy, organizing, protest, and political change led by people like Mandela transformed this global order and brought prosperity to billions of people.

"At the outset, his struggle was particular to this place, to his homeland – a fight to end apartheid, a fight to ensure lasting political and social and economic equality for its disenfranchised non-white citizens," Obama said. 

"But through his sacrifice and unwavering leadership and, perhaps most of all, through his moral example, Mandela and the movement he led would come to signify something larger," he added. "He came to embody the universal aspirations of dispossessed people all around the world, their hopes for a better life, the possibility of a moral transformation in the conduct of human affairs."

Obama had four rules for people who want to continue Mandela’s work.

1. Fight inequality

“Madiba shows those of us who believe in freedom and democracy, we’re going to have to fight harder to reduce inequality and promote lasting economic opportunity for all people,” he said.

Obama said that progressive taxation, laws that break up monopolies, strong collective bargaining rights, universal health care, anti-corruption efforts, and investments in scientific research are some of the goals that have to be pursued.

Read More: What The Panama Papers Have to Say About Inequality and Poverty

He also sought to criticize the extreme accumulation of wealth, which drew some of the largest applause in the audience in a country with the world’s greatest inequality.

“A few dozen individuals control the same amount of wealth as the poorest half of humanity,” he said. “That’s not an exaggeration; that’s a statistic.”

“There’s only so much you can eat, there’s only so big a house you can have, there’s only so many nice trips you can take,” he said. ”It shows a poverty of ambition to just want to take more and more and more, instead of saying, ‘Wow, I have so much, who can I help, how can I give more and more and more?”

2. Recognize the shared humanity of all people

Former President Obama honoring Nelson Mandela: “Madiba reminds us that no one is born hating another person because the color of his skin... People must learn to hate. And if they can learn to hate, they can be taught to love. For love comes more naturally to the human heart.” pic.twitter.com/hSgiRkWKFv

— CNN (@CNN) July 17, 2018

“We are bound together by a common humanity and each individual has inherent dignity and worth,” Obama said. “It’s surprising that we have to affirm this truth today.”

“When embraced, it delivers practical benefits, because it ensures that a society can draw on the skills, talents of all its people,” he said. “Just ask the French football team that won the World Cup, because not all of those folks look like Gauls to me, but they’re French.”

Obama then criticized any country that thinks human rights are secondary ideals.

Read More: UN Accuses US of Human Rights Violations for Separating Migrant Families

“Dissent, women participating, the rights of minorities to equal treatment, the rights of people not to be beat up and arrested ... We have to be careful to say that somehow that doesn’t have to apply to us, that those are somehow Western ideas, rather than universal imperatives,” he added.

3. Promote democracy

Obama spent much of his speech warning about the risks of democratic decline and urged people to get involved on the grassroots level.

“Democracy is about more than just elections,” he said. “Focus more on the grassroots — that’s where democratic legitimacy comes. Not from the top down, not from abstract theories, but from the bottom up.”

Read More: What Mexico's New President-Elect Means for Poverty and Inequality

He also urged the audience to fight for a fress press and an objective basis of reality, and warned against the rise of misinformation.

“We see it in the growth of state-sponsored prograpanda, we see it in internet-driven fabrication, the blurring of lines between news and entertainment, and the utter lack of shame among political leaders who are caught in a lie and double down and lie some more,” he said.

“As with the denial of rights, the denial of facts runs counter to democracy, its could be its undoing, that’s why we have to zealously guard media.”

4. Empower young people

Obama: "Keep believing. Keep marching. Keep building. Keep raising your voice. Every generation has the opportunity to remake the world. Mandela said, 'Young people are capable when aroused of bringing down the towers of oppression and raising the banners of freedom.'" (via CBS) pic.twitter.com/b1fvNPFCgA

— Kyle Griffin (@kylegriffin1) July 17, 2018

Obama said that Mandela’s legacy will be carried on by the world’s youth and spoke about several young people his foundation is currently working with in South Africa.

For example, Abaas Mpindi from Ghana started the Media Challenge Initiative to promote a robust African media network.

And Caren Wakoli from Kenya started the Emerging Leaders Foundation African to nurture the next generation of freedom fighters.

Read More: This South African Activist Uses Cell Phones to Fight Poverty

“That’s what we need right now,” Obama said. “We don’t just need one leader. We don’t just need one inspiration. What we badly need right now is that collective spirit. And I know that those young people, those hope-carriers, are gathering around the world.”

He cited the words of Robert Kennedy: “Our answer is the world’s hope. It is to rely on youth. It’s to rely on the spirit of the young.”

“So young people who are listening," Obama continued, “my message to you is simple: Keep believing. Keep marching. Keep building. Keep raising your voice. Every generation has the opportunity to remake the world."

The Global Citizen Festival: Mandela 100 is presented and hosted by The Motsepe Foundation, with major partners House of Mandela, Johnson & Johnson, Cisco, Nedbank, Vodacom, Coca Cola Africa, Big Concerts, BMGF Goalkeepers, Eldridge Industries, and associate partners HP and Microsoft.