“You shall not murder.”
“If the thief is found breaking in, and he is struck so that he dies, there shall be no guilt for his bloodshed.”
“Whoever curses his God shall bear his sin. And whoever blasphemes the name of the LORD shall surely be put to death.”
“Whoever kills any man shall surely be put to death.”
1 Samuel 17:50
So David prevailed over the Philistine with a sling and a stone, and struck the Philistine and killed him.
In order to answer this apparent contradiction, we must make a distinction between killing someone and committing murder. Murder is the unlawful taking of a life, while killing may be lawful or unlawful. The establishment of capital punishment actually extends back to the Noahic Covenant when God declared, “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).
Even before this, Cain was afraid of the other members of his family seeking to kill him after he had murdered his brother Abel (Genesis 4:13–15).1 In the cases outlined in Scripture, taking the life of another in the name of justice was not murder. The question poses a false dilemma in that killing does not have to be always right or always wrong—God has provided qualifications.
Because man is made in the image of God, the death of a human is not taken lightly. In the laws given to Israel through Moses, those sins that were worthy of death were detailed. Leviticus 19 is one such place where these commands are given. Since these are commands directly from God and God cannot lie, we understand that there must be no contradiction in the commands. Those who committed sexual sins were to be justly killed, but only upon the clear affirmation of their crime established by witnesses.
The Bible provides many circumstances under which the taking of a life is legally allowed by Scripture.
As the author of the first five books of the Bible, Moses would not have written contradictory ideas. If we allow for killing to be wrong in every case, when a person carried out capital punishment, as commanded by God, they would have to be killed for the taking of a life. Then their life would be demanded, and so on until humanity was left with one. Extending the logic allows us to see how absurd the claim of a contradiction truly is.
The Bible provides many circumstances under which the taking of a life is legally allowed by Scripture. Killing another person in an act of self defense (Exodus 22:2) was permitted with no consequences. There are examples of God calling the people to war against other nations to punish them for their sins. When Joshua led the children of Israel into the Promised Land, God commanded the Israelites to utterly destroy the idolatrous peoples who inhabited the land (Deuteronomy 20:16–17). A list of their sins can be found in Leviticus 18, including incest, murdering children, and so on. When God called Israel to war against those in the Promised Land, then He was permitting the killing in this situation, making men His agents of justice, as in the case with capital punishment.
The killing of Goliath by the young David was, likewise, justified in the eyes of God. In fact, David was angered by the way that Goliath blasphemed God and met him in battle. David did not trust in himself, but in the Lord to deliver Goliath into his hands. This is an example of continuance of the war the Israelites had been engaged in with the inhabitants of the Promised Land, as directed by God.
God repeatedly chose war and capital punishment as a way to bring judgment on peoples and individuals who were acting in defiance of His will by doing great sin. He ordained the killing as a punishment to accomplish His purposes in the world.
This should give an idea of seriousness of sin. In the eyes of a perfect and holy God, one sin is worthy of death (Genesis 2:17). Since we are all sinners, we are all under the death sentence already. In essence, we are all on “death row,” and those who murder or do other terrible sins as described in Scripture, simply had their wait on “death row” shortened.
God hates sin, especially those that lead to any situation where a human life is lost. His holy nature and subsequent hatred of sin make the taking of a life acceptable only in the rarest of cases. We should never seek to minimize the taking of a life—a life made in the image of God. Remember that taking a life for justifiable reasons is only necessary because we live in a world of sin. The perfect creation would not have required death for any reason.