Baker was born in Marlow, New Hampshire, the son of Isaac Baker and Abigail Kidder. He studied at Wilbraham Academy in Massachusetts where Wilbur Fisk, an influential Methodist theologian, was principal of the school. In 1828, Baker converted and joined the church, and two years later he entered the first class at Wesleyan University in Middletown, Connecticut. Baker became a teacher at Newbury Seminary in Vermont (1833). Several professors, including Baker, began offering regular theological classes in 1841, and when a portion of the seminary building was converted into a theological school, Baker became the first professor of theology in American Methodism. Baker resigned his professorship in 1844 to become the pastor of churches in Manchester and Rochester, New Hampshire (Stowell 29). The Methodist General Biblical Institute opened in 1847 in Concord, New Hampshire, and Baker returned to his academic career as a professor of homiletics and Methodist discipline. In 1852, the General Conference elected Baker to the title of bishop, and he began to travel extensively to preside over the meetings of annual conferences. Baker served as bishop until his death in 1868 (Stowell 30).

Baker supported the Union during the Civil War. The Secretary of War, Edwin Stanton, authorized the northern Methodist bishops to seize any southern Methodist church that was not being led by a loyal minister. In the spring of 1866, Baker presided over the organization of the new South Carolina conference, largely composed of freed slaves and white Unionists. Baker did not write extensively, but he published The Last Witness; or, The Dying Sayings of Eminent Christians and Noted Infidels in 1853. Two years later, he published a Guide Book in the Adminstration of the Discipline of the Methodist Episcopal Church which served as a standard reference for bishops and pastors as they worked to apply the Discipline to individual churches. Baker's primary contribution to Methodism was through his knowledge of the Constitution and laws of the Methodist Episcopal church (Stowell 30).

The Last Witness is an account of the deaths and final words of esteemed Christians such as Augustine, Martin Luther, and Bede as well as several "noted infidels" such as David Hume, John J. Rousseau, and Thomas Paine. Each entry is preceded by a biblical quote and concluded with a selection of poetry. Baker presents Dr. Young's lines as the assumption underlying the book: "Truth is deposited with man's last hour, - / An honest hour, and faithful to her trust." Baker believes that the "result of life's experiment" is known only at death and an individual's dying words reveal the soul's future. Every Christian is portrayed as dying in peace, secure in the knowledge that his spirit will "pass into the bosom of Christ" ( 7). For example, Augustine's dying words were, "O Lord, shall I die at all? - shall I die at all? Yes. Why, then, oh Lord, if ever, - why not now? O! why not now? But thy will be done. Come, Lord Jesus" (8). Those marked as infidels are presented as suffering tremendously at the end of their lives. Thomas Paine called out, "O God, what have I done to suffer so much? But there is no God! - but if there should be, what will become of me hereafter? Stay with me, for God's sake, for I cannot bear to be left alone! Send even a child to stay with me, for it is a hell to be alone!" (106). While truth is always present at the death of the Christian, when the infidel dies speaking joyful words, as in the case of John James Rousseau, Baker writes, "His private life was disgraced with immorality, and his last moments with a lie!" (103).

Stowell, Daniel W. "Baker, Osmond Cleander." American National Biography. Vol. 2. Eds. John A. Garraty and Mark C. Carnes. New York: Oxford, 1999. (29 - 30).

Other sources:

Simpson, Matthew, ed. Cyclopaedia of Methodism (1878).

Leete, Frederick D. Methodist Bishops (1948).

Harmon, Nolan B. The Encyclopedia of World Methodism (1974).