Murder, however, is not merely defined as “killing another person.” Such a definition would be overinclusive, wrongly equating killing in self-defense or killing enemy combatants in the heat of a just war with an unjust, premeditated killing of another who committed no wrong. Moreover, practices like capital punishment, which God orders as a general rule of punishment for murder in Genesis 9:5-6 and Exodus 21, would be misconstrued as inexcusable in the eyes of God. Killing another person qualifies as murder when it is (i) intentional, (ii) unjustified, and (iii) performed by someone without authority to do so.[2]

In the canon of scripture, the first act of murder is recorded in Genesis 4. After Adam and Eve were cast out from the Garden of Eden, they bore two sons: Cain and Abel. Both made offerings to the Lord, but each brought distinct items. Abel offered the “firstborn of his flock and of their fat portions,” which pleased the Lord, and Cain brought “an offering of the fruit of the ground,” for which God had “no regard.” Cain became enraged, but God nonetheless encouraged him. “Why are you angry, and why has your face fallen? If you do well, will you not be accepted? And if you do not do well, sin is crouching at the door. Its desire is contrary to you, but you must rule over it,” God said.

Notably, God assured Cain that his failure to present an acceptable offering in that instance did not prevent him from presenting an offering later. But God makes clear that Cain’s offering must be presented out of love for Him, not out of hatred for his brother Abel. Otherwise, hatred would dictate his will and conduct. Cain ignored God’s words and let hatred for his brother dictate his actions. Cain brought Abel to a field, “rose up against his brother,” and killed him, expressing a clear intent to indulge his wrath through violence. Because Cain’s decision was purely driven by sin, his conduct was unjustified.

Cain also tacitly admitted his lack of authority to kill another human being in his subsequent conversation with God. After God asks Cain about the whereabouts of his brother, Cain replies: “I do not know; am I my brother’s keeper?” In his unrepentant attitude, Cain disavows any guardianship role over his brother and tacitly admits his lack of authority to control Abel. For his actions and refusal to repent, God severely punished Cain by casting him out of the land of his family. Though intent, justification, and authority are only intuitively observed in the story of Cain and Abel, other biblical passages explicitly elucidate them as necessary elements.

For instance, the Mosaic law differentiated murder and manslaughter on the basis of intent. In the book of Numbers, the Lord allowed Israelites who “kill[ed] any person without intent” to flee to “cities of refuge” in order to avoid the death penalty enacted by an “avenger of blood.” Moreover, the Lord also provides several examples of intentional killings, such as striking another with an iron or stone tool, and unintentional killings, such as “push[ing]” someone “suddenly without enmity.”

Justification, whether one lacks moral reason to take another life, is also clearly expressed in scripture and a core component of modern American law. In Exodus 22, the Lord says, “If a thief is found breaking in and is struck so that he dies, there shall be no bloodguilt for him, but if the sun has risen on him, there shall be bloodguilt for him.” Here, modern readers can identify a principle of lethal self-defense, but may be puzzled by the distinction between day and night. They may even be more surprised that it serves as a pillar of American law.

When the U.S. Constitution was ratified, every state in the Union, except Louisiana, inherited and adopted the English common law. The common law of England enshrined a custom known as the “Castle Doctrine,” which permitted the use of deadly, defensive force only in the sanctity of one’s home. Otherwise, the English law imposed a duty to retreat from a violent situation before using self-defense. Sir Edward Coke, the English jurist, summarized the rationale for this distinction in the 1604 Semayne’s Case: “the house of everyone is to him as his castle and fortress, as well for his defence against injury and violence, as for his repose … the reason of all this is because domus sua cuique est tutissimum refugium [his own house is the safest place of refuge].”

Both the English common law and Mosaic law emphasize the inviolability of one’s home, particularly in the darkness of night. If a burglar were to attempt violence or burglarize another in this setting, a situation ancient people would recognize as shocking and grossly offensive, then deadly self-defense was justified. That said, the English common law and Mosaic law do not bind Christians to these exact standards. Other moral and legal justifications exist for killing, such as the defense of others in life threatening situations, and “self-defense” can apply in places outside one’s home. Nonetheless, this passage emphasizes how a person may be justified in taking the life of another in certain circumstances, and thus not guilty of murder.

The third element of murder, authority, is hotly debated today with respect to capital punishment, even among Christians. In fact, approximately 66% of Protestants and 58% of Catholics support the death penalty for those convicted of murder according to a 2021 Pew Research Survey. In other words, just over one-third of Protestants and 40% of Catholics believe the death penalty is unwarranted even in the most severe cases. Scripture does, however, emphasize authority as a factor separating “murder” from lawful killing.

In Genesis 9, God established capital punishment for the crime of murder in His covenant with Noah: “Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his image.” Put another way, humans cannot take the life of another except as a just punishment for the crime of murder administered by a party sanctioned by God to do so. The Mosaic law continued the tradition of capital punishment as the maximum punishment for a variety of crimes. However, it was not a mandatory punishment for any crime except for murder and could only be administered by the “avenger of blood.”

The apostle Paul alludes to this Old Testament “avenger” title in Romans 13, but identifies a new authority authorized to carry out punishment: the civil authority. “For [government] is the servant of God, an avenger who carries out God’s wrath on the wrongdoer. Therefore one must be in subjection, not only to avoid God’s wrath but also for the sake of conscience.”

However, this doesn’t mean that capital punishment is always good. Just as any tool for good can be corrupted in our fallen world, so too can the death penalty be abused, even to the point where the practice should be banned. But it is also possible that political entities can dedicate the tool toward its permissible, lawful end by ensuring it is not used against innocent parties.

Nonetheless, scripture is clear that governments are ordained by God, divinely imbued with the authority to bear the sword to punish evil and promote what is good (Romans 13:1-7). Life itself is one such basic good. In the words of Saint Thomas Aquinas, “inasmuch as every substance seeks the preservation of its own being, according to its nature: and by reason of this inclination, whatever is a means of preserving human life, and of warding off its obstacles, belongs to the natural law.” If the government takes no action to secure this basic good, it becomes guilty of dereliction of duty. That duty includes protecting the sanctity of unborn human life from abortion, an intentional, unjustified killing of an innocent child. Life belongs to God. Only He, or those He so sanctions, may take the life of another according to his Perfect will.

The Christian desires God’s perfect will, a world where a culture of life and respect for human dignity triumphs and where abortion is completely and permanently nonexistent. In light of this, any policy framework designed to advance or promote abortion, whether as an end in and of itself or as the means for selfish political ambition, contravenes God’s moral law. It is not acceptable under any Christian framework to argue that the government has no business in prohibiting the practice of abortion, whether that argument stems from political self-interest, modern libertarian sensibilities, or sheer apathy toward the unborn.