Why does Rauschenbusch argue that “the salvation of individuals” is not sufficient to address social problems?

The correct answer to this open question is the following.

Rauschenbusch argued that “the salvation of individuals” is not sufficient to address social problems because that was a promise for the afterlife. People's problems had to be addressed to improve their conditions.

We are talking about Baptist pastor and philosopher, Walter Rauschenbusch(1861-1918). He was part of the movement known as the Social Gospel, which invited people to think that social conditions had to improve to have a better and just life, not only under the promise of heaven. His ideas transcended and influence civil rights leaders like Dr. Martin Luther King Jr.

the hereditary right of a monarch to rule from the mandate of heaven

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they liv