May Christians serve as punitive agents, such as soldiers or policemen, for the civil government?
There are several denominations which hold pacifist views. Some, such as Quakers, refuse to serve in any capacity where killing might be involved. Others, such as the Amish, reject all ties to civil authority. To answer your question well, I would like to broaden the discussion to whether a Christian may participate in governmental activities.
Paul makes it very clear that governments do not exist by their own desire. They exist solely by the authority of God. "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" (Romans 13:1-2). To argue that a Christian may not serve in government is to argue that holding governmental offices is a violation of God's will -- yet such cannot be the case.
Though Matthew left his position as a tax collector to follow Jesus, other tax collectors remained in their position. Zacchaeus was a chief tax collector (Luke 19:2). When he repented of his sinful behavior, there is no indication that he left his job. (Luke 19:8-10). In the parable of the Pharisee and the publican, the tax collector was praised for his humility and not because he abandoned his occupation (Luke 18:13-14).
Probably the best evidence is a statement found near the end of Paul's letter to the Philippians. "All the saints greet you, but especially those who are of Caesar's household" (Philippians 4:22). According to William Barclay, the phrase "Caesar's household" does not mean those who were kin to Caesar. Caesar's household was the imperial civil service with members throughout the world. The palace officials, secretaries, revenue clerks, and administrators were all members of Caesar's household. Paul is sending greetings from Christians who worked in the bureaucracy of the Roman government.
Too, recall the occupation of the Ethiopian eunuch. "And behold, a man of Ethiopia, a eunuch of great authority under Candace the queen of the Ethiopians, who had charge of all her treasury, and had come to Jerusalem to worship" (Acts 8:27). The eunuch was converted, but nowhere is there any mention of him renouncing his position in the Ethiopian government. At the end of Romans 16:23 we find mention of another treasurer. "Erastus, the treasurer of the city, greets you." Here was a Christian who served in government as a city treasurer.
Therefore, we must conclude that Christian can be involved in government. However, the original question was whether Christians can be involved in positions where the enforcement of law might be necessary.
Once again, we need to turn to Paul's statements about the government. "For he is God's minister to you for good. But if you do 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" (Romans 13:4). Government is God's servant to take vengeance on those who do evil. Such duties might require the killing of wrongdoers, as the phrase "for he does not bear the sword in vain" indicates. It is true that vengeance belongs to God, "Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, "Vengeance is Mine, I will repay," says the Lord" (Romans 12:19). But what Paul is stating just a few verses later is that God has delegated some of His authority for vengeance to earthly governments. Governments do not take their own vengeance, they are merely enforcing the authority granted to them by God. Albert Barnes once wrote, "When a magistrate inflicts punishment on the guilty, it is to be regarded as the act of God taking vengeance on him; and on this principle alone is it right for a judge to condemn a man to death. It is not because one man has by nature the right over the life of another, or because society has any right collectively which it does not like individuals; but because God gave life, and because He has chosen to take it away when a crime is committed, by the appointment of magistrates, and not by coming forth Himself visibly to execute the laws." It is God who told mankind, "Surely for your lifeblood I will demand a reckoning; from the hand of every beast I will require it, and from the hand of man. From the hand of every man's brother I will require the life of man. Whoever sheds man's blood, by man his blood shall be shed; for in the image of God He made man" (Genesis 9:5-6). Pay careful attention to this command. Man is required to execute the judgment of God against a man who has committed murder.
Jesus confirmed this in his conversation with Pilate. "Then Pilate said to Him, "Are You not speaking to me? Do You not know that I have power to crucify You, and power to release You?" Jesus answered, "You could have no power at all against Me unless it had been given you from above. Therefore the one who delivered Me to you has the greater sin."" (John 19:10-11). Jesus agreed that Pilate had the right to release him or to execute him. However, Jesus pointed out that Pilate only had that right because God granted it to him.
Peter also stated that governments exist to punish evildoers. "... to governors, as to those who are sent by him for the punishment of evildoers and for the praise of those who do good" (I Peter 2:14). If governments have the right to take punitive action and Christians are allowed to work for governments, then it must follow that Christians can serve in capacities where they make have to take punitive action.
If we search through the Scriptures, we find examples of people in such occupations. When John the Baptist calls for the repentance of the Israelites, "Then he said to the multitudes that came out to be baptized by him, "Brood of vipers! Who warned you to flee from the wrath to come? "Therefore bear fruits worthy of repentance, and do not begin to say to yourselves, 'We have Abraham as our father.' For I say to you that God is able to raise up children to Abraham from these stones. "And even now the ax is laid to the root of the trees. Therefore every tree which does not bear good fruit is cut down and thrown into the fire." So the people asked him, saying, "What shall we do then?" He answered and said to them, "He who has two tunics, let him give to him who has none; and he who has food, let him do likewise." Then tax collectors also came to be baptized, and said to him, "Teacher, what shall we do?" And he said to them, "Collect no more than what is appointed for you." Likewise the soldiers asked him, saying, "And what shall we do?" So he said to them, "Do not intimidate anyone or accuse falsely, and be content with your wages"" (Luke 3:7-14). Notice again that tax collectors were not told to leave their jobs, nor were soldiers. Instead, they were told to live within the means granted to them by their occupation. Cornelius was an officer in the Roman army (Acts 10:1-2), yet he was described as a god fearing man. True, he was not saved at that time, but nothing indicates that he left his position after becoming a Christian.
The strongest evidence, though, is found in the conversion of the Philippian jailer. "And when it was day, the magistrates sent the officers, saying, "Let those men go." So the keeper of the prison reported these words to Paul, saying, "The magistrates have sent to let you go. Now therefore depart, and go in peace."" (Acts 16:35-36). After his conversion, described in Acts 16:32, we find that the man was still working for the government as a jailer.
"What if the government is corrupt?'"
When people are involved in government, we must expect corruption to exist. "If you see the oppression of the poor, and the violent perversion of justice and righteousness in a province, do not marvel at the matter; for high official watches over high official, and higher officials are over them" (Ecclesiastes 5:8). Such is the nature of mankind. However, we must also recognize that a government's authority comes to it from God. When a government official takes action that exceeds his authority and violates the commands of God, then God's commands overrule. This is what Peter told the Sanhedrin council, the Jewish high court when it ordered them to stop preaching in the name of Jesus. "But Peter and the other apostles answered and said: "We ought to obey God rather than men."" (Acts 5:29). Governing officials need to realize that they function as God's representatives to the people. If they misbehave, God will judge the judges. "God stands in the congregation of the mighty; He judges among the gods. How long will you judge unjustly, and show partiality to the wicked? Selah Defend the poor and fatherless; do justice to the afflicted and needy. Deliver the poor and needy; free them from the hand of the wicked" (Psalm 82:1-4). A person working for the government cannot blindly follow orders. He must always be conscious that he ultimately works for God. If his superiors do not like this, that is their problem.
"What if it is not a 'Christian' government?"
When Paul stated that all governments exist by the authority of God, the world was under the rule of the Roman government, which was most certainly not acting by Christian principles. Still, we must remember that God did not give two sets of laws, one for the Christian and another for the non-Christian. Both are held to the same standards. Hence if a non-Christian, acting as an agent for the government, can take a life without sin, then so may the Christian.
"How can you love someone and take his life?"
First, you must understand that the loss of life is the result of someone committing a grave sin. The death penalty is given as a consequence of sin. If it is wrong to apply penalties to the actions of a criminal then you might as well claim it is wrong to punish children when they err. Yet, God tells us that parents punish because they love their children. "He who spares his rod hates his son, but he who loves him disciplines him promptly" (Proverbs 13:24, see also Hebrews 12:7-11). Discipline is an expression of love because a parent understands that it will benefit the child in the long run. A government that does not enforce its laws does not love its citizens.
When Paul was unjustly arrested and held for two years without resolution, he made this statement. "For if I am an offender, or have committed anything deserving of death, I do not object to dying; but if there is nothing in these things of which these men accuse me, no one can deliver me to them. I appeal to Caesar." (Acts 25:11). Paul acknowledged that the government had the right to punish him if he had committed a crime, including giving him the death penalty. In his particular case, no crime was committed, so he argues that this branch of the Roman government was exceeding its authority.
Then too it should be remembered that the law to love your neighbor as yourself was first expressed in the law of Moses. "You shall not take vengeance, nor bear any grudge against the children of your people, but you shall love your neighbor as yourself: I am the LORD" (Leviticus 19:18). This is the same law that was in effect when God sent Israel to destroy the Amalekites (I Samuel 15:1-3). Obviously, God did not see a conflict between these two commands. When a person carries out the will of God in punishing a wrong-doer, the executor of justice does not incur guilt (Numbers 35:27).
"In a war you could have Christians fighting against Christians."
True. As I stated before, every decision by a government is not necessarily just, including the decision to go to war. It is up to the Christian to decide whether the war is justified or not before entering battle. We cannot pass any blame off on the government for making the wrong decision if we decide to join in. "So then each of us shall give account of himself to God" (Romans 14:12). Now those in government might disagree with our conclusion and we may have to suffer the consequences of that disagreement. Yet always the Christian remembers that he serves God first and foremost.
As an example, the Bible clearly teaches that Christianity may not be spread by warfare. Jesus stated, "My kingdom is not of this world. If My kingdom were of this world, My servants would fight, so that I should not be delivered to the Jews; but now My kingdom is not from here" (John 18:36). Paul also argued, "For though we walk in the flesh, we do not war according to the flesh. For the weapons of our warfare are not carnal but mighty in God for pulling down strongholds, casting down arguments and every high thing that exalts itself against the knowledge of God, bringing every thought into captivity to the obedience of Christ, and being ready to punish all disobedience when your obedience is fulfilled" (II Corinthians 10:3-6). Hence, the Crusades of the Middle Ages were violations of God's will. Those who participated in them sinned against God and their fellow men.
"Christianity is a religion of peace."
Again, this a true statement. In a prophecy concerning the Christian era, Isaiah said, "Now it shall come to pass in the latter days That the mountain of the LORD'S house Shall be established on the top of the mountains, And shall be exalted above the hills; And all nations shall flow to it. Many people shall come and say, "Come, and let us go up to the mountain of the LORD, To the house of the God of Jacob; He will teach us His ways, And we shall walk in His paths." For out of Zion shall go forth the law, And the word of the LORD from Jerusalem. He shall judge between the nations, And rebuke many people; They shall beat their swords into plowshares, And their spears into pruning hooks; Nation shall not lift up sword against nation, Neither shall they learn war anymore" (Isaiah 2:2-4, see also Isaiah 11:9). These and other similar prophecies were fulfilled when Jews and Gentiles joined the church. "For He Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity" (Ephesians 2:14-16).
It ought to take a lot to get a nation following Christian principles to go to war. But we must recognize that the entire world does not follow Christ. Governments still have the right to defend its citizens. On an individual scale, we must do our best to live in peace, even though peace will not always be obtained. "If it is possible, as much as depends on you, live peaceably with all men" (Romans 12:18). I believe the same principle can be applied to governments. As much as depends on a government, they should live in peace. But we sadly realize that some things are out of our control.
What about you?
Individuals may decide that they are uncomfortable with executing judgment on behalf of a government. This is perfectly fine. Paul taught, "Do you have faith? Have it to yourself before God. Happy is he who does not condemn himself in what he approves. But he who doubts is condemned if he eats, because he does not eat from faith; for whatever is not from faith is sin" (Romans 14:22-23). However, at the same time, it is clear that the Scriptures teach that a Christian may be involved in government, including those duties which involve executing judgment.