Lewis's interest in the idea of a "social gospel" aligns with his two passions, which are Christianity and social justice. The social gospel was a movement that emerged in the late 19th and early 20th centuries in North America and Europe, which sought to apply Christian principles to social problems, such as poverty, inequality, and injustice. This movement emphasized the importance of social activism, and its advocates called on Christians to work for social reform and to address the needs of the poor and marginalized.
Lewis was deeply committed to his Christian faith and believed that it called on him to work for social justice and to address the social problems of his time. He was particularly concerned with issues such as racism and poverty, and he saw the social gospel as a way to connect his Christian beliefs with his passion for social justice. In his own work as a civil rights activist, Lewis often spoke about the importance of the social gospel and the need for Christians to be engaged in the struggle for justice and equality.