Question: "What is the difference between "you shall not murder" and "you shall not kill"?"
Answer: The King James Version (KJV) of the Bible renders the sixth commandment in Exodus 20:13 and Deuteronomy 5:17 as “Thou shalt not kill.” This wording gives the impression that it is always wrong to take a human life, with no exceptions. It is a wrong impression, for the Bible elsewhere allows for the execution of certain criminals (Genesis 9:6) and killing in the context of warfare (1 Chronicles 19:18). So the command “Thou shalt not kill” cannot be taken in an absolute sense.
In fact, the KJV’s wording of “Thou shalt not kill” is needlessly broad and inexact to the point of impairing clarity. Nearly all modern translations, including the New King James Bible, correctly render the original Hebrew wording as “You shall not murder” (NIV) or “Do not murder” (CSB). The Amplified Bible words it this way: “You shall not commit murder (unjustified, deliberate homicide).”
The Old Testament uses over half a dozen different Hebrew words for the taking of a human life. In Exodus 20:13, the Hebrew word used is rasah, which means “murder.” It is the same word that the KJV correctly renders elsewhere as “murder” or “murderer,” including all eleven times that rasah appears in Numbers 35:17–31. Oddly, when they came to the sixth commandment, the KJV translators chose to translate the word as “kill” instead of “murder.” “Thou shalt not kill” is an incorrect and inconsistent translation.
That mistranslation has created needless confusion and personal, moral conflict for centuries. Christians have debated with each other—and struggled in their own minds—over whether to serve in the military during war time, to use deadly force as a police officer, or even to protect their own families from homicidal attacks. It’s unfortunately true that protecting a nation, protecting society, and protecting loved ones sometimes require killing, but that is different from murder. The command “Do not murder” does not apply to justified killing in the course of one’s duty.
The mistranslation of Exodus 20:13 has also caused believers and skeptics alike to question the reliability of the Bible and the character and justness of God. After all, after commanding the Israelites not to “kill” anyone, God orders them to kill criminals for capital crimes (Exodus 21:12–29), Israelites who worshipped the gods of Moab (Numbers 25:1–8), all Midianite males and non-virgin females (Numbers 31:1–18), and the pagan societies of Canaan (Deuteronomy 2:30–36; Joshua 6; 1 Samuel 15:1–3). Capital punishment for the crime of murder was, in fact, the first commandment God gave to Noah after the flood (Genesis 9:6).
Plainly, the Bible distinguishes between a justified killing and murder, that is, unlawful (not legally justified) homicide in which the perpetrator intentionally kills another person. The penal codes of nations around the world have historically held a similar distinction. So what God forbids in the Ten Commandments is murder, specifically, not killing, in general.