Reinhold Niebuhr was a Protestant theologian best known for his study of the task of relating the Christian faith to the reality of modern politics and diplomacy. He is a crucial contributor to modern just war thinking.
Niebuhr was born in Wright City, Missouri, USA, the son of a liberally minded German Evangelical pastor, Gustav, and the brother of Helmut Richard Niebuhr. Niebuhr decided to follow in his father's footsteps and enter the ministry. He attended Elmhurst College, Illinois (where today stands a large statue of him), graduating in 1910, subsequently going to Eden Seminary, St. Louis, Missouri. Finally he attended Yale University where he received his Bachelor of Divinity Degree in 1914 and was a member of Alpha Sigma Phi Fraternity. In 1915, he was ordained a pastor. The German Evangelical mission board sent him to serve in Detroit. The congregation numbered 65 on his arrival and grew to nearly 700 when he left. The increase was partly due to the tremendous growth of the automobile industry which was centered in that region.
During his pastorate, Niebuhr was troubled by the demoralizing effects of industrialism on the workers. He became an outspoken critic of Henry Ford and allowed union organizers to use his pulpit to expound their message of worker's rights. Niebuhr documented inhuman conditions created by the assembly lines and erratic employment practices.
In 1928, Niebuhr became Professor of Practical Theology at Union Theological Seminary in New York. Before arriving at the seminar, Niebuhr captured the meaning of his personal experience at his Detroit church in his book Leaves From the Notebook of a Tamed Cynic. While teaching theology at Union Theological Seminary, Niebuhr influenced Dietrich Bonhoeffer of the anti-Nazi Confessing Church.
During the outbreak of World War II, the pacifist leanings of his liberal roots were brought under challenge, and he began to distance himself from the pacifism of his more liberal colleagues, becoming a staunch advocate for the war. Niebuhr soon left the Fellowship of Reconciliation, a peace-oriented group of theologians and ministers, and became one of their harshest critics. This departure from his peers evolved into a movement known as Christian Realism, and Niebuhr is acknowledged as its primary advocate. Christian Realism provided a more tough-minded approach to politics than the idealism that was held by many of Niebuhr's contemporaries. Within the framework of Christian Realism, Niebuhr became a supporter of US action in World War II, anti-communism, and the development of nuclear weapons.