There is no biblical justification for Christian involvement in secular government. Yes, you read that correctly. There is no justification for voting for candidates no matter what promises they make and there is no justification for the pursuit of an office in government as an individual. Earthly government is the secular and satanic response to the leadership of God. The world's governments exist as an affront to the leadership of Jesus.
If we look at God's instruction to Israel, He makes it clear on the Mountain of Sinai in Exodus 20, "Thou shalt have no other god's before me." This means God is number one, there is no other. Seeking guidance and following another, other than the one true God, is the rejection of God and His leadership and direction for our lives. If this sounds extreme, please remember God's words to Samuel when Israel demanded a king. God said do not worry, they have not rejected you and your leadership as my agent. They have rejected me (1 Sam 8: 7). From this point forward in history, Israel is only rarely following the will of God and the United States never has. It had a chance when it threw out one king, but it immediately replaced him with another king under a different name.
Christian support for local, state, and national politicians is an explicit rejection of God's direction and leadership as much today as it was then. Israel demanded a king like the surrounding nations so they would look like everyone else and have one person making decisions and he could lead them during war and times of trouble. The thing is, when a king is in charge, you will always have war and times of trouble.
When Israel demanded a king, it was an explicit rejection of God's leadership. Supporting one party or another and voting for their representatives to take office is the exact same thing today. The modern politician has claims to your property, your son, your daughter, and takes the first fruits of your labor and leaves you the crumbs. Just as God described would happen with kings.
For every Christian who thinks supporting a Republican politician is more moral because their platform is closer to biblical ideals, there is another Christian supporting a Democrat politician and thinking the exact same thing. It is one thing to be fooled by a charming politician and their promises once, but they will disappoint and fail in every manner to legislate or lead in a godly manner because they are not serving God, but Satan.
Satan controls government. Satan is the leader of the world and all of its governments. Satan offered the world and all of its governments to Jesus after His baptism. Remember these words in Matthew 4: 8-9, "Again, the devil taketh him up into an exceeding high mountain, and sheweth him all the kingdoms of the world, and the glory of them, and saith unto him, all these things will I give thee, if thou wilt fall down and worship me." Jesus rejects his offer with a restatement of the First Commandment, "Get thee hence, Satan; for it is written, Thou shalt worship the Lord thy God, and him only shall thou serve."
During the short tenure of our lives, no person can point to a politician who has embodied a Christian or biblical ethic worthy of replacing the one true God's leadership. Ron Paul would be the closest thing and he falls well short of Jesus. He has probably been the greatest politician of the modern age because he refused to lead and attempted to kibosh the efforts of the forces of Satan to engage in endless wars abroad and at home, but overall he was an abject failure and never once stopped government from doing what it wanted to do and he would have been better off staying home, delivering babies, and writing essays in opposition to government.
Government is theft and force. The government can do nothing without taking money from one pocket, or printing it behind closed doors, to give it to another. This is not charity.
Theft does not become benevolence when it is done to millions and dispensed for pet projects and the poor as a control mechanism. This is class warfare unleashed by government. I am reminded of God's word in Exodus 23, "Thou shalt not follow a multitude to do evil." This is what government is. Even the things it attempts to do that have an appearance of good, are done through theft, coercion, and threats and Christians should not be involved, nor give it the stamp of approval by voting and being involved.
The State wants you to vote. It ingrains in your brain through public indoctrination that it is your civic duty to vote and be involved in politics. Ad campaigns run year round to gain support and entice people to stay engaged. Politicians use select topics to keep the public enraged throughout the year and then brings it to a fever pitch the year of national elections and the media foments this campaign as the mouthpiece of the State.
Christians, there is no justifible reason for you to vote. There is no party that governs in a righteous manner. Your existence on the voting rolls does not add a sense of morality to the government or offer any sense of control or moderation over its behavior. Your explicit rejection of Jesus as guide and King over your life does not yield good fruit. The government is the enemy of the Kingdom of God and its agents are the warriors battling to destroy the Kingdom of God and keep people from entering it.
So what should you do Christian?
Pray for the leaders of government to leave you alone and allow you to serve God in peace. Do everything you can to be a witness for the Kingdom of God to attract more people to leave the kingdom of Satan. Our goal is to live in such a way that those subject to government are drawn to Jesus and the worship of the one true God. We want them to exit the world and enter the Kingdom of God.
Do not rock the government boat by supporting one politician or another, while claiming they are the hand of God as you revile some other politician. Your support for a politician or a party is an explicit rejection of God and creates opposition among pagans when exposed to Jesus, because they have seen Christians trumpeting one person or another and they are confused. Pagans do not know what to think when Christians cannot decide one politician is better than another, because none of them are. Pagans should see Christians rejecting secular rule, while living under the State they are in, which creates an opportunity for real choice.
Follow God or continue following Satan.