"First of all, then, I urge that entreaties and prayers, petitions and thanksgivings, be made on behalf of all men, for kings and all who are in authority, so that we may lead a tranquil and quiet life in all godliness and dignity. This is good and acceptable in the sight of God our Savior, who desires all men to be saved and to come to the knowledge of the truth." (1 Tim. 2:1-4)
A Christian's participation in politics, be it as simple as voting or complex as running for office, should match his prayers -- petitioning not for world peace but for the Church's peace in living out quiet, godly lives to accomplish the objective of educating sinners in God's saving truth. To have one objective before the throne of grace and another before the throne of men is hypocrisy. In other words, the Church always has an agenda when it relates to the powers that be -- how best to meet the Churchʼs mission here on earth. Here are some points to consider to that end:
First, the voting booth is just as sacred as the church altar. There is no sacred and secular compartments in the world -- everything is sacred. "Whether we eat or drink or whatever you do (that includes voting), do all to the glory of God" (1 Cor. 10:31). Weʼre driven by this single issue, and anything less marginalizes God.
Second, if our voting should glorify God, then our reasons for who we vote for should as well. Pragmatic reasons concerning who would best run the country or benefit my wallet must first give way to God-honoring reasons. Thereʼs a pecking order here. If I'm praying for the welfare of the Church and its mission in my culture, my vote should reflect who would be closer to seeing that happen -- voting many times between the lesser of two evils, or even not at all. While no candidate is "Godʼs" candidate in the election, some have better platforms than others in seeing our above prayers accomplished.
Lastly, accept those who may reason differently from you on which candidate can best accomplish the Church's above mission. This is similar to the "logic" of believers when it comes to eating things sacrificed to idols (1 Cor. 8) -- some could, some couldn't. But both did so before God and both were accepted in the Church. After all, if voting was allowed in the 1st Century who do you think would make a "better" Caesar in regards to the Church, Nero or Domitian?
God doesn't save republicans or democrats -- only sinners. Be careful in making the candidates or the issues the determining factor in your voting. The issue is always God -- and lost fellow-citizens needs to hear that from voting Christians.