Morality and, in particular, justice within the social sphere are important themes. Paul VI argues that the Catholic Church is concerned with moral social structures and actions by individuals in the world. Paul VI wants urban areas in which people are treated with justice, and he decries the injustices he has seen in his travels to urban areas around the globe. He argues that youth, women, workers, and emigrants should not be discriminated against and should be treated with dignity. People must treat the environment in a just and moral way because if they do not, the damaged environment will harm human beings in the future.
Paul VI rejects Marxism and socialism because they do not bring justice to the world. At the same time, individualistic liberalism is also not just. Paul VI wants justice in the world but warns against any arrangement to attempt to bring about perfect justice in the world.
Social action is also an important theme in this work. The beginning of the document calls for social action and engagement throughout the world. Individuals are called to engage in social action in a variety of ways—ranging from activities at their own workplace to work involving migrants.
The final portion of the document focuses on social action. It says that “there is a need to establish a greater justice in the sharing of goods.” This social action must not use force but must encourage cooperation and solidarity among human beings. This social action must lead to changed attitudes in individuals and changed social structures because those too can be unjust. Christians can and should work within the political sphere. Politics should be used to rectify the situations in which many people live. While there is a place for social action within politics, there are many means of correct social action. In the end, the document offers “to all Christians . . . a fresh and insistent call to action.”