This is well said by a commentator at Gotquestions.com
Christians often ask us whether they should be a Republican or a Democrat or something else, we have to listen to what the Bible says about political issues and encourage each other to make a decision from there. In all actuality, few political issues are truly spiritual issues. As an example, we may prefer lower taxes, but the Bible does not endorse low taxes; all it says is that we are to pay our taxes honestly (Romans 13:6-7; Matthew 22:15-21). Taxes and many other issues (social security, universal healthcare, education funding, prescription drugs, etc.) are not spiritual issues the Bible specifically addresses. As a result, Christians can in good conscience have disagreements on these issues.
An issue the Bible most definitely “takes sides” on is abortion. Jeremiah 1:5 tells us that God knows us before He knits us in the womb. Psalm 139:13-16 speaks of God’s active role in our creation and formation in the womb. Exodus 21:22-25 prescribes the same penalty of someone who causes the death of a baby in the womb as the penalty for someone who commits murder. This clearly indicates that God considers a baby in the womb as just as much of a human being as a full-grown adult. For the Christian, abortion is not a matter of a woman’s right to choose. It is a matter of the life or death of a human being made in God’s image (Genesis 1:26-27; 9:6). Therefore, Bible-believing Christians should strongly support candidates who are pro-life.
Another issue which is most definitely biblical is that of gay marriage. The Bible condemns homosexuality in the strongest terms possible (Genesis 19:1-13; Leviticus 18:22; Romans 1:26-27; 1 Corinthians 6:9). Gay marriage is an attack on the institution of marriage that God created to be between one man and one woman (Genesis 2:22-24). Endorsing gay marriage or even civil unions is basically giving approval to a lifestyle choice the Bible condemns as immoral and unnatural. Gay marriage, then, is an issue Christians must consider when they evaluate a candidate.
The Bible teaches that a leader in the church should be a godly, moral, ethical person (1 Timothy 3:1-13; Titus 1:6-9). This should apply to political leaders as well. If politicians are going to make wise, God-honoring decisions, they must have a basic morality on which to base the decisions they are going to have to make. So if there is a clear moral distinction between candidates, as Christians, we should choose the more moral, honest, and ethical of the candidates.
No matter who is in office, whether we voted for them or not, whether they are of the political party we prefer or not, the Bible commands us to respect and honor them (1 Peter 2:13-17; Romans 13:1-7). We should also be praying for those placed in authority over us (Colossians 4:2; 1 Thessalonians 5:17). We do not have to agree with them, or even like them, but we do have to honor and respect them. Politics is always going to be a difficult issue for Christians. We are in this world, but are not to be of this world (1 John 2:15). We can be involved in politics, but we should not be obsessed with politics. Ultimately, we are to be heavenly-minded, more concerned with the things of God than the things of this world (Colossians 3:1-2). As believers in Jesus Christ, we are all members of the same political party—monarchists who are waiting for their King to return (Revelation 19:11-16).