The US has honoured Martin Luther King Jr with a federal holiday for nearly four decades yet still has not fully embraced and acted on the lessons from the murdered civil rights leader, his youngest daughter said.

The Reverend Bernice King, who leads The King Centre in Atlanta, said leaders, especially politicians, too often cheapen her father’s legacy into a “comfortable and convenient King” offering easy platitudes.

“We love to quote King in and around the holiday. … But then we refuse to live King 365 days of the year,” she declared at the commemorative service at Ebenezer Baptist Church, where her father once preached.

The service, sponsored by the centre and held at Ebenezer annually, headlined observances of the 38th federal King holiday.

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A wreath-laying ceremony at the Martin Luther King, Jr, Memorial on Martin Luther King Jr Day in Washington (Andrew Harnik/AP)

King, gunned down in Memphis in 1968 as he advocated for better pay and working conditions for the city’s sanitation workers, would have celebrated his 94th birthday on Sunday.

Her voice rising and falling in cadences similar to her father’s, Bernice King bemoaned institutional and individual racism, economic and health care inequities, police violence, a militarised international order, hardline immigration structures and the climate crisis.

She said she is “exhausted, exasperated and, frankly, disappointed” to hear her father’s words about justice quoted so extensively alongside “so little progress” addressing society’s gravest problems.

“He was God’s prophet sent to this nation and even the world to guide us and forewarn us. … A prophetic word calls for an inconvenience because it challenges us to change our hearts, our minds and our behaviour,” Bernice King said.

“Dr King, the inconvenient King, puts some demands on us to change our ways.”

President Joe Biden was scheduled to address an MLK breakfast hosted in Washington by the Reverend Al Sharpton’s National Action Network.

Mr Sharpton got his start as a civil rights organiser in his teens as youth director of an anti-poverty project of King’s Southern Christian Leadership Conference.

“This is a time for choosing,” Mr Biden said, repeating themes from a speech he delivered Sunday at Ebenezer at the invitation of Senator Raphael Warnock, the senior pastor at Ebenezer who recently won re-election to a full term as Georgia’s first black US senator.

“Will we choose democracy over autocracy, or community over chaos? Love over hate?” Mr Biden asked.

“These are the questions of our time that I ran for president to try to help answer. … Dr. King’s life and legacy — in my view — shows the way forward.”