At section 116, the document discusses the disruption brought about by sin:
The consequences of sin, insofar as it is an act of separation from God, are alienation, that is, the separation of man not only from God but also from himself, from other men and from the world around him. "Man's rupture with God leads tragically to divisions between brothers. In the description of the 'first sin', the rupture with Yahweh simultaneously breaks the bond of friendship that had united the human family. Thus the subsequent pages of Genesis show us the man and the woman as it were pointing an accusing finger at each other (cf. Gen. 3:12). Later we have brother hating brother and finally taking his brother's life (cf. Gen 4:2-16). According to the Babel story, the result of sin is the shattering of the human family, already begun with the first sin and now reaching its most extreme form on the social level".Thus sin creates a "twofold wound", one in the sinner himself and one in the relationship with his neighbors. Because we are social creatures, because of human solidarity, every sin has social consequences of some sort.
There is also an order of sin that is explicitly social in nature:
Certain sins, moreover, constitute by their very object a direct assault on one's neighbour. Such sins in particular are known as social sins. Social sin is every sin committed against the justice due in relations between individuals, between the individual and the community, and also between the community and the individual. Social too is every sin against the rights of the human person, starting with the right to life, including that of life in the womb, and every sin against the physical integrity of the individual; every sin against the freedom of others, especially against the supreme freedom to believe in God and worship him; and every sin against the dignity and honour of one's neighbour. Every sin against the common good and its demands, in the whole broad area of rights and duties of citizens, is also social sin. In the end, social sin is that sin that "refers to the relationships between the various human communities. These relationships are not always in accordance with the plan of God, who intends that there be justice in the world and freedom and peace between individuals, groups and peoples".Social sins are acts of injustice, denials of human rights, and violations of human dignity committed on a scale larger than the individual. Furthermore, these social sins have a particular staying power:
The consequences of sin perpetuate the structures of sin. These are rooted in personal sin and, therefore, are always connected to concrete acts of the individuals who commit them, consolidate them and make it difficult to remove them. It is thus that they grow stronger, spread and become sources of other sins, conditioning human conduct. These are obstacles and conditioning that go well beyond the actions and brief life span of the individual and interfere also in the process of the development of peoples, the delay and slow pace of which must be judged in this light. The actions and attitudes opposed to the will of God and the good of neighbour, as well as the structures arising from such behaviour, appear to fall into two categories today: "on the one hand, the all-consuming desire for profit, and on the other, the thirst for power, with the intention of imposing one's will upon others.Segregation was a structural sin. Racist individuals institutionalized their personal sins in the structural sin of segregation. The civil rights movement awakened the conscience of the nation and condemned this. This led, eventually, to a national repentance which took the form of abandoning segregation. This does not mean, of course, that individuals repented of their racism. But it does illustrate the idea of structural sin and how it must be dealt with, namely, by acknowledging it and collectively repenting of it.
There are many structures of sin in the world today. There are social structures in various parts of the world that oppress women and create an atmosphere in which domestic abuse and sex trafficking flourish. Our own system is currently ordered in such a way that rich executives can drive businesses (and whole economies) into the ground, deprive workers of their jobs, and walk away with their wealth intact. Many more examples could be given.
Catholic social teaching gives us language we can use to condemn these social structures in moral terms, not just in the political terms of bad policy. Sin does not cease to be sin simply because it is committed on a grand scale.
The Compendium of the Social Doctrine of the Church