Our Catholic teaching not only calls us to serve those in need, it also calls us to work to change the structures that deny people their dignity and rights as children of God.  We believe we have a political responsibility to be informed, active citizens, who participate in the debate over the values and vision that guide our communities and our nation.  We are called to use our talents, the resources of our faith, and the opportunities of democracy to shape a society more respectful of the life, dignity and rights of the human person.  Voices of  parishioners need to be heard on behalf of those who suffer discrimination and injustice, on behalf of our land and water, our communities and neighborhoods.  We must advocate to make the system work for ALL people.
Communities of Salt and Light, USCCB pg 9

In the Catholic Tradition, responsible citizenship is a virtue, and participation in political life is a moral obligation.  This obligation is rooted in our baptismal commitment to follow Jesus Christ and to bear Christian witness in all we do.
Faithful Citizenship, USCCB