Principle #1: The Bible has just as much authority over social and political issues as it does over religious issues. When the Bible speaks, it is the top word and the final word. It is not acceptable to God to limit the Bible to only "spiritual" issues or "heart" issues, and ignore it on issues of community ethics. God demands our highest allegiance to the Bible, not to liberalism, conservatism, or whatever "ism" we prefer. If the choice is between the Bible and our favorite "ism", the "ism" has to go into the waste-basket.
Principle #2: God is present, and ultimately in charge of day-to-day operations. God is not out yonder, not paying attention. This means political humanism is a lie. God has not delegated daily management of the community entirely onto us, as if it's all on us, or that we're free to run around down here doing whatever we feel like. The book of James, chapter 5, warned business-people to remember the "if the Lord wills" factor, in all their planning. The same is true for community leadership. A short time of prayer would supply more guidance and solve more problems than endless committee meetings do.
Principle #3: God requires the same ethics from a community leader that he requires from a preacher. I've heard a saying: "We're electing a president, not a pastor." That is a godless saying. God in Genesis required Abimelech to do what was right, and return Sarah to Abram. God in Amos condemned Philistia and Ammon for war-crimes. God avenged war-crimes committed by the king of Moab against the remains of the king of Edom (Amos 2:1). God killed Herod for breaking the first commandment (Acts 12:20-23).
Principle #4: The idea of, "the ends justify the means," as an excuse for sinning in pursuit of a good goal, comes from Satan. That was Satan's pitch to Eve back in Genesis 3:4-5 -- break the commandment of God as part of attaining a desirable outcome. That was how King Herod did things. God killed a Jewish priest for acting on the principle that the ends justify the means (2 Samuel 6:1-7). God ordains moral methods as well as goals. God condemns all who say, "Let us do evil, that good may come" (Romans 3:8).
Principle #5: Preachers should beware getting bogged down in direct politics. Paul in 2 Timothy 2:4 taught that ministers, like soldiers, should not get "entangled" in civilian affairs. This principle could apply to different scenarios. It could apply to commercial endeavors, such as if a minister gets so involved with a home business that it begins to undermine his ministry. It could also apply to entanglement with secular politics. A Christian preacher speaks to community morals and ethics, but his calling as a minister overrides other otherwise-acceptable interests he might have. Christian laymen may have more liberty to participate in direct social and political matters than the pastor.
Principle #6: James 1:19 applies to political involvement. Be quick to listen, slow to talk, and slow to get angry. Calm down. Be a peacemaker. There is way too much yelling, insulting, and snide remarks being made by Christians (this applies to our conduct on the Internet, too.) There are too many of us Christians popping off about topics we barely understand. Too many clichés, and little real wisdom. We Christians must conduct ourselves with honor.