March 14, 1857, Clay County, North Carolina.
February 22, 1913, Texas City, Texas.
La Marque Cemetery, La Marque, Texas.
Son of William and Caroline Kerby, Marion was listed as a farmer in the 1880 census in Coryell County, Texas. In 1887, he married Donia Easterling in Bell County, Texas, near Temple; Donia died in May of the following year.
Marion attended the Southern Baptist Theological Seminary in Louisville, Kentucky (1890–91), then married Sallie Munson in 1892 at Hope, Texas. He went on to serve as pastor of the Little River Baptist Church in Jones Prairie, Texas (1895–99). He returned to the Southern Baptist Theological Seminary in Louisville (1899–1901), where he received Bachelor and Master of Theology degrees.
In 1908, Kerby was pastor for part of the year at the Alta Loma Baptist Church, then pastor of the Baptist Church of La Porte, Texas (1908–10). He served as a missionary in the field in 1909, then as pastor of the of First Baptist Church, Texas City (1911–13).