Among the civil rights milestones credited to Dr King's leadership before his 1968 assassination is the 1965 Voting Rights Act.
The landmark legislation included laws that eliminated barriers to voting for African Americans, who in some areas had been almost completely disenfranchised.
Mr Biden made reference to Dr King's famous "I Have a Dream" speech in his sermon.
"We all deserve liberty and justice. And it's still the task of our time to make that dream a reality because it's not there yet," he said.
Martin Luther King Jr among the leaders behind former US President Lyndon B Johnson at the August 1965 signing of the Voting Rights Act. Photo: US National Archives
King, president of the Southern Christian Leadership Conference, and Mathew Ahmann, executive director of the National Catholic Conference for Interrracial Justice, in a crowd at the Civil Rights March on Washington in 1963. Photo: US National Archives
King with organisers of the Civil Rights March on Washington in front of the Lincoln Memorial. Photo: US National Archives
King's 1963 mugshot after his arrest for protesting over the treatment of black Americans in Birmingham, Alabama.
King, right, accompanied by the Rev Ralph D Abernathy, centre, is booked by city police Lt D H Lackey in Montgomery, Alabama, for his part in the bus boycott protests, on February 23, 1956. AP
King visits the Soviet Sector border of the Berlin Wall in Bernauer Strasse. Photo: US Information Service Bonn
A 1965 telegram note requesting King's appearance before the House subcommittee on voting rights.
King with Muslim minister and human rights activist Malcolm X in March 1964. Photo: Library of Congress
King and his wife Coretta Scott King enjoying a Sammy Davis Jr performance. Picture: US National Archives
Rights watchers have warned that in many parts of the US, the right to vote is being threatened.
“State laws violate the right to vote and misinformation about the 2020 elections is eroding public faith in elections and democratic institutions,” Human Rights Watch wrote before last year's midterm elections.
Mr Biden's Democratic party failed to pass a voting rights bill that included provisions to make election day a national holiday.
It would have ensured access to early voting and mail-in ballots, and enabled the Justice Department to intervene in states with a history of voter interference.
In September, Mr Biden gave a prime-time speech warning Americans that far-right groups “promote authoritarian leaders and they fan the flames of political violence that are a threat to our personal rights, to the pursuit of justice, to the rule of law, to the very soul of this country”.
Georgia's newly elected Democratic Senator Raphael Warnock spoke before the president on Sunday, telling of America's democratic promise and its history of marginalisation.
Mr Warnock referred to the famous white monuments in the nation's capital — to founders George Washington and Thomas Jefferson, and “the Great Emancipator” Abraham Lincoln.
He quoted Mr Jefferson's famous words in the US Declaration of Independence, that “all men are created equal".
“But on the other side of the Tidal Basin, a Black man stands there with his arms folded, as if to say to Thomas Jefferson. 'Did you mean what you said?'” he said.
A memorial to Dr King sits across from the Jefferson memorial.
Mr Biden is the first sitting president to stand at Dr King's Georgia pulpit to deliver a Sunday sermon, wearing the same Catholic rosary on his wrist that his late son Beau wore on his death bed, he said.
Open Men (bonus points in brackets)
New Zealand 125 (1) beat UAE 111 (3)
India 111 (4) beat Singapore 75 (0)
South Africa 66 (2) beat Sri Lanka 57 (2)
Australia 126 (4) beat Malaysia -16 (0)
Open Women
New Zealand 64 (2) beat South Africa 57 (2)
England 69 (3) beat UAE 63 (1)
Australia 124 (4) beat UAE 23 (0)
New Zealand 74 (2) beat England 55 (2)
Scoreline
Switzerland 5
WHAT IS A BLACK HOLE?
1. Black holes are objects whose gravity is so strong not even light can escape their pull
2. They can be created when massive stars collapse under their own weight
3. Large black holes can also be formed when smaller ones collide and merge
4. The biggest black holes lurk at the centre of many galaxies, including our own
5. Astronomers believe that when the universe was very young, black holes affected how galaxies formed
UAE currency: the story behind the money in your pockets
Pot 1: Iran, Japan, South Korea, Australia, Qatar, United Arab Emirates, Saudi Arabia, China
Pot 2: Iraq, Uzbekistan, Syria, Oman, Lebanon, Kyrgyz Republic, Vietnam, Jordan
Pot 3: Palestine, India, Bahrain, Thailand, Tajikistan, North Korea, Chinese Taipei, Philippines
Pot 4: Turkmenistan, Myanmar, Hong Kong, Yemen, Afghanistan, Maldives, Kuwait, Malaysia
Pot 5: Indonesia, Singapore, Nepal, Cambodia, Bangladesh, Mongolia, Guam, Macau/Sri Lanka
