In Populorum Progressio, Paul VI offers focused reflection on the Christian themes of solidarity, options for the poor, and Christian anthropology. He explains that all people have the same supernatural destiny and are called to contribute to the building up of the human community. This shared destiny brings people in unity with their brothers and sisters. A fruit of this unity is the virtue of solidarity, which entails being aware of the sufferings of others and assisting those in need.
Central to solidarity is the need to be attentive to the situation of the impoverished. Paul acknowledges that the voices of the impoverished tend to go unheard because they lack the wealth and power to gain the attention of others. Therefore, all people must make efforts to acknowledge the needs of others so that the poor will also have the opportunity to contribute to society. In particular, Paul states that private property should be expropriated when owners abuse their land while others go without necessities. Further, Paul encourages the development of a world fund and calls for reflection on how international trade relations can be equalized.
Paul also makes frequent mention of the need to develop a genuine understanding of humans. Paul states that economic development alone is not sufficient. He argues that for people to be fully human, they must have a peaceful family and political community, education, moral formation, and spiritual orientation toward their origin and end. Paul argues that Christian social teaching is more than a set of principles and rules because this teaching promotes the fulfillment of human life. Promoting Christian social teaching, then, is not an imposition on others but an act of charity expressed for the benefit of others.