Jesus taught us to love our neighbor as ourselves and to care for the poor. Liberation theology does much to bring those issues to the forefront. However, the problem with liberation theology is that it distorts the Gospel message from one of salvation and transformation to mere social work.
All forms of oppression, slavery, and injustice have their roots in personal sin. Liberation from personal sin is what eliminates those secondary effects. Liberation theology essentially focuses on the symptoms rather than the disease. It has tendencies towards Marxism (focus on class struggle rather than individual sin) and tends to focus on systems rather than persons. This branch of theology has also been used to justify violence.
Authentic Christianity declares that Jesus Christ died for sin and offers us new life through grace. Liberation theology has a tendency to focus on reforming unjust earthly systems with only secondary regard for the sins of the individuals involved. While it is certainly praiseworthy and holy to commit one’s life to opposing injustice, we need to remember that Jesus died so that we might have eternal life, not just better access to social programs. What good are all the social programs in the world if we are still slaves to sin? And how can those social programs not be abused by those who control them if they are still ruled by original sin?
The Church condemns injustice, oppression, and slavery. The Church seeks to rouse the conscience of those who can affect change. The Church preaches that we are commanded (not suggested) to love one another. But all these things must be done in accordance with the truth of the Gospel.
The idea that the Christian message is primarily focused on secular and economic matters is indeed heretical, but the idea that actually trying to help the poor through personal charity and creating just systems in society is indeed a moral obligation of Christians is perfectly orthodox. Popes John Paul II and Benedict XVI often spoke of the need for a preferential option for the poor.
If a Catholic school is teaching liberation theology, it would depend upon the context. If it is presented within a historical review of theologies of the twentieth century, then it can be helpful and informative. If, however, it is presented as authentic Catholic theology, then a complaint should be made first to the appropriate people on campus (e.g., the head of the theology department or the university president). If that fails, a complaint could be lodged with the appropriate local ordinary, who has authority over the school.