It's a lesson we're always learning. We need to understand, also, that on points of public policy we can have differing views and positions. Good citizens and good Catholics can have divergent views on public policy matters. Government is an honorable thing. Civic virtue is, in fact, a virtue.
Public service is an honorable profession because government itself is honorable.
We likewise need to apply good Christian principles to political life. Religion and politics are both concerned with public policies - as such, they are joined at the hip. Citizenship is a virtue, the American bishops have declared. Participation in the political process is an obligation we have as Christians. Otherwise we abandon the field to our Ancient Enemy and give him free reign to wreck havoc upon us.