One of the important public policy issues that unites many mainline Christians, Roman Catholics, Orthodox churches, and a great number of evangelicals is the need for immigration reform.  You can read recent news on this subject from the National Council of Churches here and additional information from Faith in Public Life here.  I'll be in DC this week with other faith leaders talking about ways to effectively communicate the moral issues involved with reform. 

Church World Service offers this great resources for additional study: 

The Bible as the Ultimate Immigration Handbook: Written by, for, and about migrants, immigrants, refugees, and asylum seekers