The King family was joined by members of the civil rights movement and Interior Secretary Ken Salazar in celebrating the reopening of Ebenezer, called the cornerstone of King's legacy. Salazar said the church is "hallowed ground for a nation still very much in progress."
"To be here this afternoon is to feel that history and remember out personal connection," Salazar told the crowd gathered in the building, which was closed to visitors in 2007.
Ebenezer's Heritage Sanctuary has been restored to its original appearance from 1960-68, when King co-pastored there with his father.
Work began on the $8 million project in 2000, and includes a return of the original pulpit furniture and furnishings.
It also restored King's most important title: preacher, said his youngest daughter, Bernice King, who delivered the keynote address at the ceremony.
"I'm happy that so many people will come to this place ... that will stand as a reckoning point for millions of people all around the world," she said.
"You must remember always the pastor and the pastor's mission: To redeem the soul of America. He loved God. He obeyed God, and he loved God's people."
Excerpts of King's most famed sermons were piped into the sanctuary before the ceremony began.
"Much comes to my mind as I stand here this afternoon, because I grew up in Ebenezer," a smiling Martin Luther King III, the president and chief executive officer of The King Center, told the audience.
His daughter, Yolanda Renee King, opened the ceremony by ringing a liberty bell near the pulpit.
The Rev. Joseph Lowery attended the ceremony and said he had many fond memories of the church, where he often met to discuss strategy for the Southern Christian Leadership Conference, which he founded with King in 1957.
"I can't tell you how it feels to me to be standing here in this spot, in this place, at this hour," Lowery said from the pulpit where King delivered his sermons more than four decades ago. "This church and this ministry have been significant in the history of this country for a long time. I thank God that it remains here to be seen."
King was born just blocks from Ebenezer on Auburn Avenue in downtown Atlanta and grew up in the church.
His father, known as "Daddy King," preached there and was a local civil rights activist.
King is buried next to the church, in a crypt alongside his widow, Coretta Scott King.
The Rev. Raphael G. Warnock, the current pastor of Ebenezer and a King scholar, said Friday's ceremony was a restoration not only of a building but also of a movement.
"We must rediscover lost values," he said. "The black church has been the conscience of America. We held vigil for that which is truest and best in the American spirit. We still have work to do. We can't be silent."
During the ceremony, King's only living sibling, Christine King Farris, was made an honorary park ranger by National Park Service Director Jon Jarvis.
"This day is a day of tremendous emotional resonance for me," said Farris. "I've tried to share as much as I can, being the last survivor of the nuclear family."
Ebenezer is the anchor of the Martin Luther King Jr. National Historic Site, which has more than 700,000 visitors annually.