ATLANTA --- The impending inauguration of the nation's first black president is a huge step toward realizing Martin Luther King Jr.'s dream of racial equality, but there is still work to be done, Dr. King's nephew told a large crowd Monday at the church where the civil rights leader once preached.

Isaac Newton Farris, the president of The King Center, told the jubilant crowd on what would have been Dr. King's 80th birthday that the election of Barack Obama was built on a foundation laid by Dr. King and was a "gigantic leap" toward the fulfillment of Dr. King's dream. The sanctuary of Ebenezer Baptist Church was packed, with dozens of people left outside.

"There is definitely a spiritual connection between these two events," Mr. Farris told the mostly black congregation that erupted in applause at any mention of Mr. Obama's name.

The Rev. Rick Warren -- a Southern Baptist who opposes gay marriage -- gave the King Day keynote address, urging the crowd to follow Dr. King's example of service and selflessness. The Rev. Warren is also set to give the inauguration invocation today.

"Tomorrow when I pray the invocation for my friend, Dr. King and a whole host of witnesses will be shouting," the Rev. Warren said. "Martin Luther King was a mighty tool in the hand of God. But God isn't through. Justice is a journey and we're getting further and further along."

The Rev. Warren backed a recent ballot measure banning same-sex marriage in his home state of California. Mr. Obama's decision to give the Rev. Warren a role in the inauguration sparked protests from the gay community and the National Organization for Women.

The Rev. Warren's appearance at the annual King holiday service also was not without controversy. About 100 protesters gathered across the street. Mr. Farris defended The King Center's choice of the Rev. Warren as keynote speaker, saying he embodies many of the ideals espoused by Dr. King.

Mr. Farris told the crowd that as long as disparities persist in health care, education and economics, Dr. King's work remains undone.

"The dream was not about an individual or any race of people attaining power," Mr. Farris said. "It was a human dream."

Dr. King preached at Ebenezer Baptist Church from 1960 until his death in 1968.

Only one of Dr. King's three living children, Bernice, attended the Monday event. His sister, Christine King Farris, led the ceremony. Dr. King's son Martin Luther King III was in Washington already and his other son Dexter King -- who lives in California -- did not attend. Their other sister, Yolanda, died in 2007.