The Social Gospel was a Christian intellectual movement that was most prominent in the early 20th century United States and Canada. The movement applied Christian ethics to social problems, especially issues of social justice such as economic inequality, poverty, alcoholism, crime, racial tensions, slums, unclean environment, child labor, inadequate labor unions, poor schools, and the danger of war. Theologically, the Social Gospellers sought to operationalize the Lord's Prayer (Matthew 6:10): "Thy kingdom come, Thy will be done on earth as it is in heaven." They typically were post-millennialist; that is, they believed the Second Coming could not happen until humankind rid itself of social evils by human effort. The Social Gospel was more popular among clergy than laity. Its leaders were predominantly associated with the liberal wing of the Progressive Movement, and most were theologically liberal, although a few were also conservative when it came to their views on social issues. Important leaders include Richard T. Ely, Josiah Strong, Washington Gladden, and Walter Rauschenbusch.