Obama honors Martin Luther King at Washington church

Women have their photo taken at the Martin Luther King, Jr. memorial on his 83rd birthday in Washington January 15, 2012.

WASHINGTON (Reuters) - President Barack Obama celebrated the legacy of slain civil rights leader Martin Luther King Jr. with his family on Sunday, clapping and swaying to the boisterous strains of "Amazing Grace" at a historic Washington D.C. Baptist church.

On the eve of the holiday marking King's birthday, the president, First Lady Michelle Obama and their daughters, Sasha and Malia, attended a service at Zion Baptist Church.

The Reverend Keith Byrd Sr. called on congregants to keep King's legacy alive and welcomed the first family.

"[The Obamas] came here to worship, and we want them to worship," Byrd said. "Bless you and thank you for joining us."

Deacon Hendri Williams, who also spoke at the service, closed his remarks by highlighting King's belief in the importance of religion and quoted from a letter King wrote from the Birmingham, Alabama, city jail to his fellow clergy in 1963.

King, a Baptist pastor, said the church was "not merely a thermometer that recorded the ideas and principles of popular opinion; it was a thermostat that transformed the mores of society," Williams said quoting from the now famous letter.

A recipient of the Nobel Peace Prize in 1964, King, was assassinated in 1968.

The Zion Baptist church was founded in 1864 by African Americans who migrated to Washington from Fredericksburg, Virginia.

(Reporting By Alexandra Alper; editing by David Bailey.)