As a measure supporting my church's effort to grow, I've distributed business cards with discussion starters in a couple of coffee shops. One of the questions is, "Is there such a thing as a moral tax policy?" I think there is.
Particularly a tax code like ours is chock full of moral assumptions. Among those assumptions is that the more wealthy you are the more you afford to pay to support the country.
For more information, I'm about to start reading Part IV of Jim Wallis's God's Politics, titled "Spiritual Values and Economic Justice."