First of all, I believe we should let our Christianity influence our voting. As believers we should pray about each election and cast our votes accordingly. We are also called to pray for our leaders and those in authority over us. 2 Tim. 2:1-2 says, "I urge, then, first of all, that requests, prayers, intercession and thanksgiving be made for everyone—for kings and all those in authority, that we may live peaceful and quiet lives in all godliness and holiness." Verses 3 and 4 says why: "This is good, and pleases God our Savior, who wants all men to be saved and to come to a knowledge of the truth."
Instead of constantly criticizing whatever party is in power we should first pray for them! Yes we can speak out against injustice and evil practices. We should stand up for those less fortunate. However, in that, we should model Christ. Would Jesus speak in anger or love? Would He send emails proclaiming certain leaders evil and stand with picket signs and protesters in front of buildings? Would He argue over birth certificates and which countries are being invaded and why?
I believe He would quietly and effectively get to the heart of the matter. Through direct questions Jesus always spoke directly to the heart. He spoke to the need, the thirst.
Jesus was not a politician. He had ample opportunity in Israel to speak against and for political systems when He was on the earth. Instead He went about His Father's business.
I have no problem with Christians participating in the political forum or running for office. However there will be no perfect system on this earth. History is littered with "Christian" governments. It was these very governments which brought us the Crusades, the Inquisitions, etc.
You cannot legislate morality. If you could than the 10 commandments would have been enough! Instead the 10 commandments showed us our need for a Saviour. Everyone in government can become a Christian but unless the people seek God for themselves you will still have sin running rampant across the nation. As a matter of fact you may have it running rampant in the "Christian" government as well.
2 Chronicles 7:14 is often quoted in re. to Christians in politics. Reading this Scripture in context, though, I find that God spoke to Solomon and the people during the temple dedication and said if His people humbled themselves He would heal their land. This was a specific promise to Israel. It was not a promise that if we elect Christian politicians than all would be right in the world. You can say it typifies God's character and you would be right. To say anything else though is a gross misuse of Scriptures.
If we would put as much energy into cementing our own relationship with God and sharing His truth of salvation with others as we did in attacking and promoting political parties THEN we could truly make a difference.
Matthew 6:33 says to seek first God's Kingdom and His righteousness.
Run the race. Work out your salvation daily. Focus on Him and His truth!