Theology Detail
Applied to: Sanctity of innocent life
Exodus 20:13 is the sixth commandment: “Thou shalt not kill.” It is the most concise and authoritative prohibition of unjust killing in Scripture, and it governs the entire biblical ethic of the sanctity of human life.
“Thou shalt not kill.” (Exodus 20:13)
The sixth commandment is part of the Decalogue, given by God directly to Israel at Sinai (Exodus 20:1). It belongs to the “second table” of the law—the commandments governing man’s duty to his neighbor. It is the shortest of the ten commandments: two words in Hebrew (lo’ tirtsach).
The Hebrew word ratsach refers specifically to the unlawful, unjust killing of a human being. It is distinguished from other Hebrew words for killing (harag, muth) that can include lawful execution, warfare, or killing of animals. Ratsach is the word used for murder (Numbers 35:16–21), manslaughter (Numbers 35:22–25), and any unjust taking of human life. The KJV renders it “kill,” but the moral scope of the commandment is specifically the unlawful taking of innocent human life.
The Decalogue was not given to Israel as mere tribal legislation. The Reformed tradition (WCF 19.2) teaches that the moral law, summarized in the Ten Commandments, is a transcript of God’s eternal moral will and is binding on all people in all ages. The sixth commandment is not abrogated by the New Testament; it is deepened (Matthew 5:21–22) and universally applied.
The Westminster Larger Catechism unpacks the sixth commandment with remarkable breadth:
Duties required (WLC 135): “All careful studies, and lawful endeavours, to preserve the life of ourselves and others by resisting all thoughts and purposes, subduing all passions, and avoiding all occasions, temptations, and practices, which tend to the unjust taking away the life of any.”
Sins forbidden (WLC 136): “The taking away the life of ourselves, or of others, except in case of publick justice, lawful war, or necessary defence; the neglecting or withdrawing the lawful and necessary means of preservation of life.”
The principle is clear: the sixth commandment requires the active preservation of innocent human life and prohibits its unjust destruction. It applies not only to the act of killing but to complicity, neglect, and the withdrawal of protection.
Christ Himself deepens the sixth commandment in the Sermon on the Mount, teaching that even unjust anger toward a brother violates its spirit (Matthew 5:21–22). If anger without cause is condemned, how much more the deliberate, premeditated destruction of an innocent life?
Romans 13:9 includes “Thou shalt not kill” among the commandments summarized by the law of neighbor-love. James 2:11 treats it as part of the indivisible moral law. The sixth commandment is not an isolated rule; it is woven into the fabric of the entire biblical ethic.
Proverbs 6:16–17 lists among the things the LORD hates “hands that shed innocent blood.” The emphasis on innocent blood is critical. The commandment does not prohibit all taking of life in every circumstance; it prohibits the unjust taking of life, with special weight on the destruction of those who have done no wrong.
The application to the abortion question is direct, not inferential.
If the unborn child is a living human being—and Scripture consistently treats the unborn as persons known to God, formed by God, and called by God (Psalm 139:13–16, Jeremiah 1:5, Luke 1:41–44)—then the deliberate destruction of the unborn is a violation of the sixth commandment. It is the unjust taking of innocent human life.
The Westminster Standards do not qualify the sixth commandment by age, stage of development, location, or desiredness. The commandment protects human life as such. An unborn child who has committed no crime and poses no threat to the mother’s life is, by definition, innocent.
This is a direct teaching, not a prudential inference. The sixth commandment says “Thou shalt not kill.” The question is only whether the unborn are human beings. Scripture’s answer to that question is consistently yes.
The sixth commandment does not prohibit all taking of life without exception. The Westminster Standards explicitly carve out “publick justice, lawful war, or necessary defence” (WLC 136). Genuine medical emergencies where the life of the mother is at imminent risk may involve tragic choices that fall under the category of necessary preservation of life, not elective destruction of life.
The commandment also does not settle every question of legal penalty or enforcement mechanism. It establishes the moral principle—the unjust taking of innocent life is forbidden—and leaves questions of civil implementation to prudential wisdom operating under that principle.
It would be an overreach to use this commandment to condemn every difficult medical situation involving pregnancy as “murder” without careful distinction. It would be an equal overreach to use the existence of hard cases to void the commandment’s clear prohibition of the elective, deliberate destruction of innocent human life.
“Thou shalt not kill” is God’s direct, unqualified prohibition of the unjust taking of human life. The Reformed tradition reads this commandment broadly: it requires the active protection of life and forbids not only murder but complicity, neglect, and the withdrawal of lawful protection. Applied to the unborn—whom Scripture treats as human persons—the sixth commandment prohibits elective abortion as a violation of God’s moral law. This is not a partisan proof-text. It is the plain moral teaching of the Decalogue, affirmed by the Westminster Standards and the whole counsel of Scripture.