God is the one who gives and takes life. As 1 Samuel 2:6 says, “The LORD kills and brings to life; he brings down to Sheol and raises up.” He can choose to take us out of the world any time he wants (Deut 32:39; Job 1:21; 12:10; 14:5; 34:14-15; Isa 45:7; Lam 3:38; Dan 5:23). He is sovereign over life and over death. Murder is wrong because only God has the authority to take life. Because only God gives life, only God has the right to take life. To kill an innocent person is to usurp the authority only God has and put ourselves in the place of God. Because only God has the right to take life, how could it ever be just for one person to kill another? On what basis could God order someone to kill another person?
One principle we must take into consideration when answering this question is that it is essential to distinguish between those who are innocent and those who are deserving of death. Murder is the taking of innocent life, not all life. Lying is not telling the truth to those to whom the truth is owed, not all acts of deception. God commanded that those who murder be put to death: “Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his own image” (Gen 9:6). All men have dignity and value because they are made in the image of God unlike animals who can be killed for food. It is exactly because man has value that murderers must be punished with death so that the punishment fits the crime. Destroying the image of God is a crime worthy of the greatest punishment.
God commanded Israel to kill the Canaanites because of the greatness of their sins (Deut 18:9-14). It is just for Israel to kill pagan idolaters in warfare because they are great sinners deserving of death. God allowed for the Israelites to use lethal force to defend themselves against thieves (Exod 22:2). The failure to distinguish between those who are innocent and those who are guilty leads to much of the confusion surrounding this question. Everyone whom God has ever ordered to be put to death was either someone deserving of death or in corporate solidarity with those who deserved to die. As in the case of Achan, everyone who was associated with him had to die for the guilt to be purged from Israel (Josh 7:24-26). But this extreme example is an exception to the general rule that children are not to be put to death with their parents (Deut 24:16).
God is just to order human government to kill those who are deserving of death because the government is an extension of God’s sovereignty when it is acting on his behalf (Rom 13:1-6; 1 Pet 2:13-14). When God tells the government to shed the blood of men who are guilty of murder, the government is acting as God’s instrument. It is not human government who is ultimately taking life, but God who is doing so through them. The government is not sinning when it takes the lives of those who are evil because it is fulfilling the Word of God. Only God can take life, but he has delegated this authority to the government. God has also revealed in his Word that it is appropriate to take life when necessary to protect the innocent from those who try to kill them (Neh 4:13-14; Esth 8:11; Ps 82:4; Prov 24:11; Acts 7:24). In these situations, the one who takes life is exercising an authority delegated to him by God. It is only just for man to take the life of another man in specific situations where God has revealed that doing so is appropriate. In such cases, it is God who is taking life through the means he has ordained.