Social Gospel was a prominent Protestant movement in the late 19th and early to mid 20th century that attempted to apply Christian principles to social problems. Part of Christian "modernism" with a strong emphasis on social justice the movement was a rival to evangelical and fundamentalist Christianity.
In the United States prior to World War I, the Social Gospel was the religious wing of U.S. "progressive" politics which had the aim of combating injustice, suffering and poverty in society.
Sometimes called "Christian socialism" the movement was especially influential in Canada and led many ministers to become active in the socialist movement in the form of the Cooperative Commonwealth Federation and later the New Democratic Party. Social Gospel is still influential in Canada's United Church and in the Anglican Church but has less influence in the United States. It also remains influential among "Christian socialist" circles in Britain in the Church of England, Methodist and Calvinist movements.
Arguments against social gospel usually come from conservatives, evangelicals and fundamentalists who see social gospel as left wing, secular or theologically suspect.