John Green Harrison was born on April 27, 1869, to Green Berry and Rhoda Ellafair Mayo Harrison. He graduated from Mercer University in 1889. He graduated from the Southern Baptist Theological Seminary with the Th.M. degree in 1899. He did graduate level work at the University of Chicago and the University of Berlin in Germany. He received honorary degrees from Mercer University and Louisiana College during his lifetime. Harrison was ordained as a Southern Baptist minister in 1906 and served as president of the Hiawassee Institute and pastor of Tattnall Square Baptist Church in Macon, Georgia. During his career, he served as a trustee, professor, and dean of the School of Christianity at Mercer University. He was secretary of the Georgia Baptist Education Board. He was also a member of the Georgia State Boards of Welfare and Education. During his time at Mercer, he was a professor of philosophy. He was also a special agent to the Holding Commission. He married Bessie Winn Gilmore on December 28, 1893. She died in 1902. He later married Ruth Barrett on June 22, 1911. The couple had 3 children: John, Jr.; William, and Martha. John Green Harrison died on January 28, 1934, in Harrison, Georgia.