Question: When did Reinhold Niebuhr write "Moral Man and Immoral Society" and argue Christian Realism?

Related documents: [0]  [DOC] Christian Realism is a philosophical perspective developed by the theologian and public intellectual Reinhold Niebuhr in the late 1940s and early 1950s. Niebuhr argued that the Kingdom of God cannot be realized on earth because of the innately corrupt tendencies of society. Due to the injustices that arise on earth, a person is therefore forced to compromise the ideal of the kingdom of heaven on earth. Niebuhr argued that human perfectibility was an illusion, highlighting the sinfulness of humanity at a time when the world was confronted by the horrors of experiences such World War II, the reigns of both Adolf Hitler and Joseph Stalin, and the Holocaust. The movement was in part a reaction to the Social Gospel movement. Numerous American political figures have been influenced by Christian realism, such as Martin Luther King Jr., Jimmy Carter, Barack Obama and Hillary Clinton. [END] 
[1]  [DOC] Karl Paul Reinhold Niebuhr ( ; June 21, 1892June 1, 1971) was an American theologian, ethicist, commentator on politics and public affairs, and professor at Union Theological Seminary for more than 30 years. Niebuhr was one of America's leading public intellectuals for several decades of the 20th century and received the Presidential Medal of Freedom in 1964. A public theologian, he wrote and spoke frequently about the intersection of religion, politics, and public policy, with his most influential books including "Moral Man and Immoral Society" and "The Nature and Destiny of Man", the second of which Modern Library ranked one of the top 20 nonfiction books of the twentieth century. Andrew Bacevich labelled Niebuhr's book "The Irony of American History" "the most important book ever written on U.S. foreign policy." Historian Arthur Schlesinger Jr. described Niebuhr as "the most influential American theologian of the 20th century" and "Time" posthumously called Niebuhr "the greatest Protestant theologian in America since Jonathan Edwards." [END]  
Answer: the twentieth century
the twentieth century