CLAIM: God commands that killing is morally wrong, but then he commands murderers to be killed (Ex. 21:12). Is it right to kill or not?
RESPONSE: God doesn’t universally prohibit the taking of human life in any and every situation. The command here is for an individual to kill another individual without a sufficient ethical warrant. To put this simply, all murder is killing, but not all killing is necessarily murder.
The term “murder” (rāṣaḥ) doesn’t necessarily refer to premeditated or intentional killing. The term was sometimes used for unintentional killing (Num. 35:11), or what we might call “man slaughter.” However, Israelite legislation took intent into account (Ex. 21:12-14), and the term “usually implies violent killing of a personal enemy.”
In the original Hebrew, there were seven different words for killing. Of these seven terms, the word “murder” (rāṣaḥ) was the best word to use to describe the unjustified taking of human life. If Moses meant to refer to killing in general, he would have used the Hebrew word harag. Therefore, the Bible is against murder—not necessarily killing. For instance, this command does not apply to execution (Ex. 21:12), self-defense (Ex. 22:2), or an accidental death (Deut. 19:5).
 William White, “2208 רָצַח,” ed. R. Laird Harris, Gleason L. Archer Jr., and Bruce K. Waltke, Theological Wordbook of the Old Testament (Chicago: Moody Press, 1999), 860.
 R. Alan Cole, Exodus: An Introduction and Commentary, vol. 2, Tyndale Old Testament Commentaries (Downers Grove, IL: InterVarsity Press, 1973), 167.
 Kaiser writes, “If any one of the seven words could signify ‘murder,’ where the factors of premeditation and intentionality are present, this is the verb.” Gaebelein, Frank E. (General Editor), and Walter C. Kaiser Jr., “Exodus,” in The Expositor’s Bible Commentary: Genesis, Exodus, Leviticus, Numbers, ed. Frank E. Gaebelein, vol. 2 (Grand Rapids, MI: Zondervan Publishing House, 1990), 424-425.