In the late 1800s, the Social Gospel movement taught the idea that all Christians should attempt to improve the world in which they lived. They should do so by ameliorating the plight of the poor and the powerless.
The late 1800s was a time in which wealth and power was becoming concentrated in the hands of a few. This was the era of the “robber barons.” It was also the era in which many people espoused the idea of Social Darwinism. During this time, many people felt that unfettered capitalism was a good thing because it forced everyone to compete. Those who were not “fit” enough to compete became poor and those who were fit became wealthy. Thus, everyone in society got the sort of life they deserved based on their levels of talent and effort.
The Social Gospel fought back against these ideas. It promoted the idea that the most important law in Christianity was “love thy neighbor as thyself.” They felt that those who were not poor ought to try to create a world that was just. They felt that middle and upper class Americans ought to create a society that treated the poor more fairly. Therefore, they argued for things like the creation of labor unions. They argued that everyone should work together to try to improve society and make it fairer and more equal.
This was a philosophy, then, which called on Christians to work together to solve the social problems brought on by industrialization and economic inequality. It was emphatically a philosophy that called for the uplift of the poor and powerless, not for the unchecked competition of Social Darwinism.