You shall not murder. (Exodus 20:13)

The commandment "Thou shalt not kill" (KJV) is found in Exodus 20:13 and again in Deuteronomy 5:17. The Hebrew word translated as "kill" in the King James, "ratsach", is actually more accurately translated as "murder" as it is translated in the NIV and NASV translations. The concept is that of a premeditated act of murder or revenge, not with killing in general. God Himself commanded the Israelites to slaughter a great many godless people in their conquest of the Promised Land, so the commandment regarding murder obviously does not forbid killing in general. There is a critical difference between murder and killing, and it deals almost solely with the motive.

"Anyone who strikes a man and kills him shall surely be put to death. However, if he does not do it intentionally, but God lets it happen, he is to flee to a place I will designate. But if a man schemes and kills another man deliberately, take him away from my altar and put him to death." (Exodus 21:12-14)

Exodus 21:12-14 delineates the difference in guilt between premeditated murder and killing someone accidentally, or in an uplanned act of self-defense...the murderer is to be killed, whereas the one who had no intention of killing someone, though he may suffer unpleasant consequences, is to remain alive.

Whoever sheds the blood of man, by man shall his blood be shed; for in the image of God has God made man. (Genesis 9:6)

This is why life is precious, murder is wrong, abortion is wrong, euthanasia is wrong, suicide is wrong. Life is to be defended. Notice the number of Old Testament laws that are punishable by death. In short, the law says that those whose actions show disrespect toward God or human life are to be put to death. The defense of life often requires the taking of life. And for any of you white/beige/brown/black/male/female supremacists out there, we're talking about all human life here. Every human being is made in the image of God. There is no Scriptural justification for any other position.

"You have heard that it was said, ‘Eye for eye, and tooth for tooth.’ But I tell you, Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also. And if someone wants to sue you and take your tunic, let him have your cloak as well. If someone forces you to go one mile, go with him two miles. Give to the one who asks you, and do not turn away from the one who wants to borrow from you.
"You have heard that it was said, ‘Love your neighbour and hate your enemy.’ But I tell you: Love your enemies and pray for those who persecute you, that you may be sons of your Father in heaven." (Matthew 5:38-45)

If anyone does not provide for his relatives, and especially for his immediate family, he has denied the faith and is worse than an unbeliever. (1 Timothy 5:8)

Notice that Jesus did not say, "If someone strikes your neighbor on the right cheek, have your neighbor turn to him the other also," or, "Give someone else's stuff to the one who asks you." If you are a spouse, parent, guardian, or member of a body of believers, then you have a financial, emotional, and/or spiritual obligation to fulfill; thus, an attack on your life is effectively an attack on your family. There must be a balance between showing love to an enemy and protecting those whom God has placed under your protection. It is the balance between justice and mercy.

"Put your sword back in its place," Jesus said to him, "for all who draw the sword will die by the sword. Do you think I cannot call on my Father, and he will at once put at my disposal more than twelve legions of angels?" (Matthew 26:52-53)

If you are one who "draws the sword"--in other words, you turn to your sword, rather than the Lord, in times of trouble--then you "will die by the sword." Note that Jesus does not command Peter to throw away his sword, but to put it "back in its place." He is correcting Peter's perspective, reminding him to live by the Spirit (Galatians 5:25) rather than the sword. The sword is only beneficial when it is used in a Spirit-led manner, and placing trust in one's sword will ultimately result in defeat (see Psalm 20:6-8). The sword has definite uses, but overcoming the world is not one of them (see John 16:33, 1 John 4:4).

Also see Proverbs 3:5-6, 16:9, 19:21

Then Jesus asked them, "When I sent you without purse, bag or sandals, did you lack anything?"

"Nothing," they answered.

He said to them, "But now if you have a purse, take it, and also a bag; and if you don’t have a sword, sell your cloak and buy one. It is written: ‘And he was numbered with the transgressors’; and I tell you that this must be fulfilled in me. Yes, what is written about me is reaching its fulfilment."

The disciples said, "See, Lord, here are two swords."

"That is enough," he replied. (Luke 22:35-38 NIV)

One could draw a literal mandate of two swords for every 12 believers, although that does not seem to be Jesus' meaning. Either way you look at it, though, Christ clearly desired that the disciples be armed for deterrence (not aggression) and, if necessary, self-defense. Having a couple of swords around was one of the most effective ways to deter criminal activity.

Literalists might insist that the scripture only authorizes the possession of swords. I maintain that the Biblical precepts relating to swords apply equally to any other weapons that can be used for personal defense--rocks, knives, sticks, hatchets, baseball bats, firearms, etc. Even an automobile can be used as a defensive weapon. The question is not, "What is a sword?" but rather, "Are you reasonably prepared to defend yourself and those around you from physical attack, and is your trust in the Spirit of God rather than in your own planning and power?"

After a cursory search of the Scripture for other references to the concept of self-defense, I came up with the following list of passages, which deal not only with the right of self-defense, but also with the responsibility to protect others, balanced with our mandate as children of God to seek peace and to love our enemies. The Scripture must be understood from its full perspective, not from select portions pulled out of their context, so I urge you to read the passages surrounding each verse, and commit prayer and study to this matter for yourself.