Jollyblogger has an excellent post on being Christian and being politically involved. It's an excellent trip through the various things the Bible says relevant to why it's good to be political involved and bad to identify some political party or nation with Christianity. This is about as balanced as you can get on this topic. I agree with all his main points. Unfortunately, I find myself disagreeing with him on quite a few of his minor and tangential points, and I can't resist picking nits by mentioning those (since I can't wholeheartedly recommend a post this glowingly if it has so many things I disagree with without also registering that disagreement).