The Bible says there is “a time to love, and a time to hate; a time for war, and a time for peace.” (Ecclesiastes 3:8). How does this square with the Christian idea of loving one's neighbour and loving one's enemies always? Let's think about World War II against Hitler for a moment. What Hitler did was oppress the innocent Jews, and it is right for us to hate such evil. The Bible says:
He has told you, O man, what is good; and what does the LORD require of you but to do justice, and to love kindness, and to walk humbly with your God? (Micah 6:8)
We are to imitate the characteristics of God, both in doing justice as well as in being kind and merciful to others. In the case of war, it is right for us to fight against someone like Hitler to bring about the liberation of the innocent Jews. To fight in a war against a Hitler-like character, we do exercise both justice and mercy. It is justice to bring down Hitler's regime, and it is mercy on the innocent Jews to set them free. Mercy comes through the execution of justice. James says:
For judgment is without mercy to one who has shown no mercy. Mercy triumphs over judgment. (James 2:13)
We can read it this way... the one who showed no mercy, such as Hitler, is shown no mercy when judgement comes, but he is the one who is judged. When judgement came it was the innocent Jews who were shown mercy. Justice and mercy go hand in hand, and “mercy triumphs over judgement”. That is, when judgement comes it is the innocent who are victorious. Psalm 136 says, for example, that God “overthrew Pharaoh and his host in the Red Sea, for his steadfast love endures forever” (Psalm 136:15). To some this sounds like a contradiction; that God killed the Egyptians by drowning because His love endures forever!? But God showed His love and mercy toward Israel in the destruction of the Egyptians who had put them into slavery. And God showed His justice for this atrocity committed by the Egyptians.
As Christians we ought to resist evil. But God has appointed government for this purpose – to establish laws and police, to enforce laws and reprimand law breakers. And when it comes to it, governments are to engage armies both for the defence of the nation against evil, and to bring evil to justice. Referring to national government, Paul says:
For he [the one in authority] is the servant of God, an avenger who carries out God's wrath on the wrongdoer. (Romans 13:4)
There is such a thing as a just war; for example, when a government becomes the oppressor of the people, Christians ought to fight on the right side of a war which will overthrow that government. But this doesn't mean that we cease to love our enemies. If we were soldiers in World War II and came face to face with the enemy, there would still be a desire that they would repent of their evil, and we would not enjoy one bit doing what we might have to do. Our hearts would still go out to them, and if any opportunity arose to minister to them we ought to extend the offer of the gospel in the hope that they might turn to God.
Whilst I would affirm that there are situations in which a Christian should fight for a just cause, we would have to examine ourselves in such a situation to see whether we are indeed fighting for the right reason. When hatred starts to become our motivation, we need to turn away from that. The Bible tells us that Christians will be persecuted and must endure persecution. When and how we should fight back if we are persecuted takes wisdom. As I have said, God has appointed government as the “avenger” of wrongdoing, and we would be perfectly in our rights to take someone to court. And if the courts are our persecutors when we have done no wrong, then persecution may be something we have to bear. Christians are to be faithful even to death; so while our enemies may resort to all manner of evil against us, we must never become like them in violence and wickedness. Because we know that there is a judge in heaven who will bring all things to justice, whether in this life or the next, we can endure persecution for the sake of the gospel and remain loving toward those who persecute us, pleading with them to change their ways.
Civil disobedience is not against the Christian faith; if a law were passed which said I could not own and read a Bible, I would disobey such a law. Once, when Jesus was speaking in the temple, they came to Him and asked “Is it lawful to pay taxes to Caesar?” So Jesus asked for a coin. The thing to note about coins at that time is that they had an image of Caesar on them, and an inscription which read “Caesar Augustus Tiberius, son of the Divine Augustus.” The Roman emperors were more and more demanding to be worshipped as gods. Jesus had the people look at this coin and said “Render to Caesar the things that are Caesar's, and to God the things that are God's.” Taxes should be paid because the state provides us with services such as roads. But worship belongs to God. So where Caesar had the right to demand taxes, he had no right to demand worship. We are to render to the state what they have the right to demand of us; but when they would cause us to become disobedient to the true king, they have no right and civil disobedience is justified. Christians in the first century did refuse to worship the emperor, which is why they were persecuted; and the Bible advocates this disobedience clearly...
And they have conquered him by the blood of the Lamb and by the word of their testimony, for they loved not their lives even unto death. (Revelation 12:11)