A group of Ethiopian sea traders in lower Manhattan refused to participate in segregated church services and formed their own congregation, naming it for their homeland and taking many free blacks from other churches with them.

Two hundred years later, the church is going back to its roots — literally.

Come September, the Rev. Calvin O. Butts III will lead a pilgrimage of about 200 church members and dignitaries on a pilgrimage to Ethiopia to mark the bicentennial anniversary of the church.

The trip, he says, will highlight an observance that begins on Tuesday and will end in November 2008, the actual 200th anniversary of the church’s origin.

“It was the first ‘mega church’ of 2,000 members in the country,” Butts said in an interview. “We want to celebrate what that experience means, we want to talk about community development, spiritual renewal, and of course the history of Abyssinian Baptist as the primary and premier religious institution in Harlem.”

Overall, Butts said, the bicentennial is intended to commemorate the spiritual, social and cultural history of the black community, and in particular “the significant role played by the churches as that community’s oldest and strongest institutions.”

Jefferson, president from 1801-1809, never visited the church, as far as is known, but Presidents John F. Kennedy and Lyndon B. Johnson did, as did Jimmy Carter as a candidate. Dr. Martin Luther King Jr. also made one appearance there in the late 1950s or early 1960s, Butts said.

The Rev. Adam Clayton Powell, pastor at the time, “was known then as ‘Mr. Civil Rights,’ but he acknowledged Dr. King,” he said.

Butts said the planned pilgrimage to Ethiopia has several purposes, including “fellowship with the Ethiopians,” missionary work, the creation of an orphanage for the offspring of AIDs victims, and a ceremony at the grave of Ethiopia’s legendary Emperor, Haile Selassie, who died in 1975, age 81, after a lifetime of defying invaders and seeking independence for his and other African nations.

The platform guest list for Tuesday’s kickoff included Gov. Eliot Spitzer, Sen. Hillary Rodham Clinton and Rep. Charles Rangel. While not expected to be present, Mayor Michael Bloomberg prepared a proclamation declaring Abyssinian Baptist Church Day.

Others on the program were Wynton Marsalis, artistic director of Jazz at Lincoln Center, who has written a Mass composition for the celebration; Cornel West, professor of religion and African American Studies at Princeton University, and Howard Dodson, chief of the Schomburg Center for Research in Black Culture, which will present a special exhibit for the bicentennial.

West and Maya Angelou are among five co-authors of a book, “Witness,” that traces the Abyssinian church’s two centuries of history.

The church occupied at least two different sites in lower Manhattan before Rev. Adam Clayton Powell Sr., moved it uptown to Harlem in 1923, according to Tai Foster, a church spokesman.

Today, the congregation is about 4,000, the largest black congregation in New York state. It is one of several Harlem churches whose dynamic, music-filled Sunday services draw crowds of European tourists.

“They come out of curiosity, and then they tell their friends back in Italy, France and Israel, and we welcome them as well,” Butts said.