From the Compendium of the Social Doctrine of the Church:
Men and women who are made “new” by the love of God are able to change the rules and the quality of relationships, transforming even social structures. They are people capable of bringing peace where there is conflict, of building and nurturing fraternal relationships where there is hatred, of seeking justice where there prevails the exploitation of man by man. Only love is capable of radically transforming the relationships that men maintain among themselves. This is the perspective that allows every person of good will to perceive the broad horizons of justice and human development in truth and goodness.
I think this insight is fascinating, and important to understanding why the Catholic Church teaches that we are to work to make people’s lives better. I guess I like this, because it shows that Catholic Social Teaching is not rooted in liberal guilt, political correctness, or any particular political ideology. We are not being asked to embrace the “social gospel” movement or turn into social workers with a few Christian words thrown in. Unfortunately, many of us have encountered the terms “social justice” and “social teaching” in settings in which Christ was often absent from the picture, or if present, he was watered-down to be a hippy social revolutionary who was crucified merely because he challenged the status-quo too many times. In other words, in many settings, social justice is not tied our transformation in Christ.
However, Catholic Social Teaching is rooted in transformation; It results from Christians having been made new, fundamentally changed by Christ and His love. Catholic Social Teaching (and subsequent action based on the Teaching) is a loving response from those who know true Love, Jesus Christ. In other words, Christ transforms us, and then we respond by acting like Christ, continuing to be formed in his image through His grace.