A. D. Williams, grandfather of Martin Luther King, Jr., celebrated his birthday on 2 January 1863, the day after the effective date of the Emancipation Proclamation. Born in Greene County, Georgia, to slaves Willis and Lucretia Williams, A. D. Williams spent his childhood on the Williams plantation. After the death of his father in 1874, A. D. and his family moved from the Williams plantation to nearby Scull Shoals, a rural community on the Oconee River. A. D.'s desire to follow his father, "a slavery time preacher," into the ministry was evident even as a child, when "it was his greatest pleasure to preach the funeral of snakes, cats, dogs, horses or any thing that died. The children of the community would call him to preach the funeral and they would have a big shout." Although he was unable to attend school because of the demands of sharecropping, the seven-year-old A. D. reportedly "attracted the people for miles around with his ability to count." Taught by several ministers in the community, Williams earned his license to preach in April 1888.
During the late 1880s and early 1890s, A. D. Williams tried to make a living as an itinerant preacher while supplementing his income with other work. An injury in a sawmill accident left him with only the nub of a thumb on his right hand. Seeking better opportunities elsewhere, A. D. Williams joined the black exodus from Greene County. In January 1893, he left for Atlanta, where he was called to the pastorate of Atlanta's Ebenezer Baptist Church.
While Ebenezer was quite small when he arrived, the church grew in strength and popularity, as did Williams. Recognizing that his long-term success as an urban minister required that he overcome academic shortcomings, Williams enrolled at Atlanta Baptist College, taking both the elementary English and the ministers' courses of study. In May 1898, Williams received his certificate from the ministerial program. While in Atlanta, Williams met his future wife, Jennie Celeste Parks, and they were married on 29 October 1899. On 13 September 1903, she gave birth at home to their only surviving child, Alberta Christine Williams, the mother of Martin Luther King, Jr.
Williams was one of the pioneers of a distinctive African-American version of the social gospel, endorsing a strategy that combined elements of Booker T. Washington's emphasis on black business development and W. E. B. Du Bois's call for civil rights activism. Early in 1917, A. D. Williams became involved in an effort to organize a local branch of the National Association for the Advancement of Colored People (NAACP). Williams—described in one account as "a forceful and impressive speaker, a good organizer and leader, a man of vision and brilliant imagination, which he sometimes finds it necessary to curb"—experienced early success as an NAACP leader. During his tenure, the branch grew to 1,400 members within five months, and the newly invigorated NAACP spearheaded a major effort to register black voters.
In 1924, Williams's daughter, Alberta Christine, married Martin Luther King, Sr., who eventually became pastor of Ebenezer. When A. D. Williams died in 1931, his obituary was effusive: "A. D. was a sign post among his neighbors, and a mighty oak in the Baptist forest of the nation," it said. "Born in the country and with limited literary preparation, his wealth of native ability, tact and application made him a man among men and a force to be reckoned with in local, state, and national economic and ecclesiastical councils. He was a preacher of unusual power, an appealing experimentalist, a persuasive evangelist, and a convincing doctrinarian."