Joe Biden marked what would have been Martin Luther King Jr’s 94th birthday with a sermon on Sunday at the Ebenezer Baptist Church in Atlanta, celebrating the legacy of the civil rights leader while speaking about the urgent need to protect US democracy.

Biden said he was “humbled” to become the first sitting president to give the Sunday sermon at King’s church, also describing the experience as “intimidating”.

“I believe Dr King’s life and legacy show us the way and we should pay attention,” Biden said. He later noted he was wearing rosary beads his son, Beau, wore as he died.

“I doubt whether any of us would have thought during Dr King’s time that literally the institutional structures of this country might collapse, like we’re seeing in Brazil, we’re seeing in other parts of the world,” Biden said.

In a sermon that lasted around 25 minutes, the president spoke about the continued need to protect democracy. Unlike some of his other speeches on the topic, Biden did not mention Donald Trump or Republicans directly.

The GOP has embraced new voting restrictions, including in Georgia, and defended the former president’s role in the attack on the US Capitol on 6 January.

“Nothing is guaranteed in our democracy,” Biden said. “We know there’s a lot of work that has to continue on economic justice, civil rights, voting rights and protecting our democracy.”

He praised Justice Ketanji Brown Jackson, who noted at a ceremony after she was confirmed it had taken just one generation in her family to go from segregation to the US supreme court.

“Give us the ballot and we will place judges on the benches of the south who will do justly and love mercy,” Biden said, quoting King.

Biden preached in Atlanta a little over a year after he gave a forceful speech calling for the Senate to get rid of the filibuster, a procedural rule that requires 60 votes to advance most legislation, in order to pass sweeping voting reforms.

“I’m tired of being quiet,” the president said in that speech.

A Democratic voting rights bill named after John Lewis, the late civil rights leader and Georgia congressman, would have made election day a national holiday, ensured access to early voting and mail-in ballots and enabled the justice department to intervene in states with a history of voter interference.

But that effort collapsed when two Democrats, Kyrsten Sinema of Arizona and Joe Manchin of West Virginia, refused to get rid of the filibuster. Sinema is now an independent who caucuses with the Democrats.

Since then, there has been no federal action on voting rights. In March 2021, Biden issued an executive order telling federal agencies to do what they could do improve opportunities for voter registration.

The speech also comes as the US supreme court considers a case that could significantly curtail Section 2 of the Voting Rights Act, the 1965 law that was one of the crowning achievements of King and other activists. A ruling is expected by June.

Biden’s failure to bolster voting right protections, a central campaign pledge, is one of his biggest disappointments in office. The task is even steeper now Republicans control the House. In advance of Biden’s visit to Atlanta, White House officials said he was committed to advocating for meaningful voting rights action.

“The president will speak on a number of issues at the church, including how important it is that we have access to our democracy,” senior adviser Keisha Lance Bottoms said.

Bottoms, who was mayor of Atlanta from 2018 to 2022, also said “you can’t come to Atlanta and not acknowledge the role that the civil rights movement and Dr King played in where we are in the history of our country”.

This is a delicate moment for Biden. On Thursday the attorney general, Merrick Garland, announced the appointment of a special counsel to investigate how Biden handled classified documents after leaving the vice-presidency in 2017. The White House on Saturday revealed that additional classified records were found at Biden’s home near Wilmington, Delaware.

Biden was invited to Ebenezer, where King was co-pastor from 1960 until he was assassinated in 1968, by Senator Raphael Warnock, the senior pastor. Like many battleground state Democrats in 2022, Warnock kept his distance from Biden as the the president’s approval rating lagged. But with Biden beginning to turn his attention to an expected 2024 re-election effort, Georgia can expect plenty of attention.

Warnock told ABC’s This Week: “I’m honored to present the president of the United States there where he will deliver the message and where he will sit in the spiritual home of Martin Luther King Jr, Georgia’s greatest son, arguably the greatest American, who reminds us that we are tied in a single garment of destiny, that this is not about Democrat and Republican, red, yellow, brown, black and white. We’re all in it together.”

In 2020, Biden won Georgia as well as Michigan and Pennsylvania, where Black votes made up much of the Democratic electorate. Turning out Black voters in those states will be essential to Biden’s 2024 hopes.

The White House has tried to promote Biden’s agenda in minority communities, citing efforts to encourage states to take equity into account under the $1tn infrastructure bill. The administration also has acted to end sentencing disparity between crack and powder cocaine offenses, scrapping a policy widely seen as racist.

The administration highlights Biden’s work to diversify the judiciary, including his appointment of Jackson as the first Black woman on the supreme court and the confirmation of 11 Black women judges to federal appeals courts – more than under all previous presidents.

King fueled passage of the Civil Rights Act of 1964 and Voting Rights Act of 1965. Members of his family attended Biden’s sermon. The president planned to be in Washington on Monday, to speak at the National Action Network’s annual breakfast, held on the MLK holiday.