Scriptural Principles of Self-Defense
The Bible instructs believers to turn the other cheek, to not resist an evil person, to bless those that persecute them, to never avenge themselves, and that all who take the sword will perish by the sword. How are we to understand these things? Is it man's moral duty to provide no defense for oneself and others? Rightly understood, the scriptures of the Old and New testaments provide sufficient cause for both the defense of self, and of others.
It should be obvious that the Bible doesn't speak specifically about firearms. It does speak about life, the taking of life, the defense of self and others, and the protection and provision of the weak and helpless.
"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."
God has created all things and has authority over all things. The image of God in man informs us that we have no authority to take life other than where God allows. The positive application of not committing murder is to protect life, which includes the life of ourselves and others. Commentary
"You shall not murder."
As is the case with Genesis 9:5-6, the prohibition against murder shows us the importance of life and the protection of it. Not only do we learn with this verse to not take life unlawfully, but we also learn that we must protect life. Commentary For more on this consult the Confessional Principles.
"If the thief is found breaking in, and he is struck so that he dies, there shall be no guilt for his bloodshed. If the sun has risen on him, there shall be guilt for his bloodshed. He should make full restitution; if he has nothing, then he shall be sold for his theft."
One principle learned in this passage is that the use of violence is for the purpose of preserving life, and not safeguarding property. The two may at times be hard to distinguish, and a person taking or damaging your property, or seeking to enter your property, may well be ready and willing to injure you or others, and it may be proper to use force against the person, but to take up a weapon ought to always be for the purpose of the preservation of life. Shooting someone walking away with your TV and posing no physical harm to you or to others, if shot, has been murdered. The person robbing you of your TV, having the means to harm you, and seeking to do so, may have force used against him without you incurring bloodguilt. The issue here is not literally daytime versus nighttime, but the possibility of making a reasonable determination of the criminals intent. At least one commentator has pointed out, also, that the person entering at night is generally aware that he has a greater chance of encountering a resident, and therefore is more likely to be a violent criminal prepared to put down any resistance he encounters. Commentary
"So it was, from that time on, that half of my servants worked at construction, while the other half held the spears, the shields, the bows, and wore armor; and the leaders were behind all the house of Judah. Those who built on the wall, and those who carried burdens, loaded themselves so that with one hand they worked at construction, and with the other held a weapon. Every one of the builders had his sword girded at his side as he built. And the one who sounded the trumpet was beside me."
God's people had the tools necessary for self-defense. They were watchful for threats and they carried with them weapons necessary to that defense. While some good commentators spiritualize this passage, "We must watch always against spiritual enemies," nevertheless the actual physical act of being prepared to defend against violence is inescapable here.
"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."
This passage is focused on the magistrate and the need to provide true justice to all regardless of position and to make certain that the poor man doesn't go without proper defense, as he is one that can easily be abused. While it does not speak directly to a physical defense against aggression, or to individuals, nevertheless it establishes a principle that applies in all of life. Men ought to care for and seek to protect those that are weak, or poor, or unable to defend themselves. It is ensuring justice to save a life from the destruction an evil man seeks to perpetuate. Many places in scripture have a similar call to the defense and care of our neighbor or those that are weak. c.f Leviticus 19:15, Isaiah 1:17, & Proverbs 31:8-9
"If you faint in the day of adversity, Your strength is small. Deliver those who are drawn toward death, And hold back those stumbling to the slaughter. If you say, “Surely we did not know this,” Does not He who weighs the hearts consider it? He who keeps your soul, does He not know it? And will He not render to each man according to his deeds?"
It is a duty to assist or rescue the innocent when they are in danger by doing anything that is within our ability and in accordance with the rest of God's word. Commentary
"Again the word of the Lord came to me, saying, “Son of man, speak to the children of your people, and say to them: ‘When I bring the sword upon a land, and the people of the land take a man from their territory and make him their watchman, when he sees the sword coming upon the land, if he blows the trumpet and warns the people, then whoever hears the sound of the trumpet and does not take warning, if the sword comes and takes him away, his blood shall be on his own head. He heard the sound of the trumpet, but did not take warning; his blood shall be upon himself. But he who takes warning will save his life. But if the watchman sees the sword coming and does not blow the trumpet, and the people are not warned, and the sword comes and takes any person from among them, he is taken away in his iniquity; but his blood I will require at the watchman’s hand.’"
Matthew Henry states that "His business is to warn sinners of their misery and danger." While the point of this passage is clearly spiritual, it presents the idea of physical defense in a positive light. Matthew Henry agrees when he states, "How much wiser are men in their temporal than in their spiritual concerns! They set watchmen to guard their houses, and sentinels to warn of the enemies' approach, but where the everlasting happiness or misery of the soul is at stake, they are offended if ministers obey their Master's command, and give a faithful warning; they would rather perish, listening to smooth things." Commentary
"But I tell you not to resist an evil person. But whoever slaps you on your right cheek, turn the other to him also."
This verse is not telling us that self-defense is unlawful or immoral. This verse speaks of a personal offense that falls short of a deadly threat or bodily harm. Deadly force is not to be used in the defense of life if a deadly threat is not present. It is clear from the context that we aren't dealing with life-ending offenses. Commentary
"But I say to you, love your enemies, bless those who curse you, do good to those who hate you, and pray for those who spitefully use you and persecute you."
Because we recognize the image of God in man, because God has created man, we are called to love our enemies and not hate them or seek to harm them. Commentators point out that we are not to seek revenge but to bless those who hate us. This is not speaking to the defense of life from an imminent threat, but to our attitude toward personal antagonists. An important principle of scriptural interpretation is that scripture interprets scripture, and that clear passages help us to rightly understand the less clear. When there are clear passages allowing the defense of life such as in Exodus 22:2-3, we should not then set a passage like this one against it. Commentary
"When a strong man, fully armed, guards his own palace, his goods are in peace."
As with Ezekiel 33:1-6 above, while this teaches a spiritual truth, it's use of a physical reality to do so indicates a positive view of that reality.
John 18:10-11 (also Matthew 26:51-52)
"Then Simon Peter, having a sword, drew it and struck the high priest’s servant, and cut off his right ear. The servant’s name was Malchus.
So Jesus said to Peter, 'Put your sword into the sheath. Shall I not drink the cup which My Father has given Me?'”
Matthew's version also states that those who live by the sword, die by the sword, which is taken by some as a renouncement of self-defense with tools that can be lethal. The context in these passages is that Jesus' task was to "drink the cup" that was before Him. When predicting His coming death in Matthew 16, Jesus responds to Peter's claim that he wouldn't allow it to happen. Jesus stated, “Get behind Me, Satan! You are an offense to Me, for you are not mindful of the things of God, but the things of men.” It wouldn't have been appropriate for Jesus to have been saved from this task. This then becomes a poor proof text to apply to all men in all situations. Regarding Matthew's statement, "for all they that take the sword shall perish with the sword," it has been explained in a variety of ways. Barnes suggests that it could be a reference to those who came to take Jesus, that since they make use of the sword against the innocent, that they will die by it. Others speak about this as a prohibition against private revenge. Jamieson-Fausset-Brown explains that Jesus was here fighting a spiritual battle with certain victory, and not needing to resort to earthly physical tools to accomplish His ends. Finally, it should be remembered that since other passages make it clear that self-defense is permissible, and since Scripture interprets Scripture, this passage can't properly be understood to mean that self-defense is never permissible. It should also be noticed that the disciples had swords in the first place. Jesus would not have been unaware that His disciples carried this tool for defense. Commentary
"Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, "Vengeance is Mine, I will repay," says the Lord."
This is not a valid argument against self-defense. God has taught us that vengeance is His. it is not self-defense to go after someone to exact revenge. If someone is not immediately threatening our life, there is no recurse through self-defense. Vengeance like that belongs to God and He will use whatever means He determines, including the civil magistrate. We must not show a lack of faith in God's word to us that He will repay. Stopping an immediate threat is moral. Pursuing someone who is not an immediate threat and taking their life would be to become a murderer.