When Jesus lived upon the earth, His nation( Israel) was ruled by Rome. The Jews hated the Romans. Roman officials often were corrupt and oppressive. On one occasion when the Pharisees wanted to get Jesus in trouble, they asked Him a question: "Is it lawful to pay taxes to Caesar or not" (Matthew 22:15-22)? If Jesus said it was wrong to pay taxes, He would be in trouble with the Roman rulers. If He said it was good to pay taxes, He would be in trouble with the Jews. They thought He was trapped. Jesus asked them to bring a Roman coin to Him. He asked them whose picture and name were on the coin. They replied, "Caesar's." Then Jesus replied: "Render to Caesar the things that are Caesar's, and to God the things that are God's" (Matthew 22:21).
Every Christian lives in two kingdoms ( nations). One kingdom is spiritual. The other kingdom is physical. We are citizens of the kingdom of Christ, which is the church of Christ (Matthew 16:18,19; Colossians 1:13). At the same time, we are citizens of an earthly nation such as Zambia, France, China etc. We must be good citizens in each kingdom. We have duties to fulfill in each kingdom.
The apostle Paul also lived during the time that Rome ruled much of the world. He was a Roman citizen (Acts 22:25-29). Nero, one of the most corrupt rulers who ever lived, was on the throne when Paul wrote: "Let every soul be subject to the governing authorities. For there is no authority except from God, and the authorities that exist are appointed by God. Therefore whoever resists the authority resists the ordinance of God, and those who resist will bring judgment on themselves. For rulers are not a terror to good works, but to evil. Do you want to be unafraid of the authority? Do what is good, and you will have praise from the same. For he is God's minister to you for good. But if you do what is evil, be afraid; for he does not bear the sword in vain; for he is God's minister, an avenger to execute wrath on him who practices evil. Therefore you must be subject, not only because of wrath but also for conscience' sake. For because of this you also pay taxes, for they are God's ministers attending continually to this very thing. Render therefore to all their due: taxes to whom taxes are due, customs to whom customs, fear to whom fear, honor to whom honor" (Romans 13:1-7).
The apostle Peter also commanded Christians to "...submit yourselves to every ordinance of man for the Lord's sake, whether to the king as supreme, or to governors, as to those who are sent by him for the punishment of evildoers and for the praise of those who do good. For this is the will of God that by doing good you may put to silence the ignorance of foolish men - as free, yet not using liberty as a cloak for vice, but as bondservants of God. Honor all people. Love the brotherhood. Fear God. Honor the king" (1 Peter 2:13-17).
Sometimes the question is asked: "What if the government commands Christians to do something which is against God's law? What if the government forbade Christians to worship God? What should we do?" If there is a conflict between man's law and God's law, then God's law must be obeyed! The Jewish officials arrested the apostles for preaching Christ. They said to them: "Did we not strictly command you that you should not teach in this name? And look you have filled Jerusalem with your doctrine and intend to bring this Man's blood on us!' But Peter and the other apostles answered and said: 'We ought to obey God rather than men"' (Acts 5:28,29). We must obey both God's law and man's law. If there is a conflict, then God's law must be obeyed even if we must disobey man's law. This is the only exception!
Some say worldly people can serve in the government, but Christians cannot. The Bible does not teach this. God has just one law. It is for all men. If it is wrong for a Christian to serve in the government, it would be wrong for anyone. If it is right for a non-Christian to serve in the government, it would be right for a Christian to do the same.
Surely, there are many temptations to do wrong if one has authority over his fellow men. It is easy to abuse power. There are also temptations to get rich by using one's authority in a dishonest way. Christians must be honest and fair in all their dealings with their fellow men. This is true in business. It is also true in government.
Must a Christian pay taxes? May a Christian show respect for his nation by saluting the flag and singing the national anthem? May he vote in an election? May he serve in a government or political office? The answer to all these questions is "yes." However, a Christian must put God and His kingdom first (Matthew 6:33). He must also be honest in all things (2 Corinthians 8:21).