John Calvin Commentary Exodus 20:13

"Thou shalt not kill." — Exodus 20:13 (ASV)

The summary of this Commandment is that we should not unjustly commit violence against anyone. However, so that God may better restrain us from all injury to others, He sets forth one particular form of it, which our natural sense abhors. For we all detest murder, so that we recoil from those whose hands are polluted with blood, as if they carried contagion with them. Undoubtedly, God intends for the remains of His image, which still shine forth in people, to continue to be held in some esteem, so that all might feel that every homicide is an offense against Him (sacrilegium).

Indeed, He does not express the reason here by which He elsewhere deters people from murder—that is, by asserting that His image is thus violated (Genesis 9:6). Yet, however precisely and authoritatively He may speak as a Legislator, He would still have us consider what might naturally occur to everyone’s mind, such as the statement of Isaiah 58:7, that man is our “own flesh”. So then, in order that believers may be more diligent in avoiding inflicting injuries, He condemns a crime, which all readily confess to be unbearable. It will, however, more clearly appear later that under the word kill is included by synecdoche all violence, striking, and aggression.

Furthermore, another principle must also be remembered: that in negative precepts, as they are called, the opposite affirmation must also be understood. Otherwise, it would not be at all consistent for a person to satisfy God’s Law by merely refraining from injuring others. Suppose, for example, that a cowardly person, not daring to attack even a child, does not move a finger to injure his neighbors—would he, for that reason, have fulfilled the duties of humanity regarding the Sixth Commandment? No, natural common sense demands more than that we should merely refrain from wrongdoing. And, without dwelling further on this point, it will be evident from the summary of the Second Table that God not only forbids us to be murderers but also prescribes that everyone should diligently seek to defend the life of his neighbor and to demonstrate in practice that his neighbor's life is precious to him. For in that summary, no mere negative phrase is used; instead, the words expressly state that our neighbors are to be loved.

It is, therefore, unquestionable that He here entrusts to our care the lives of those whom God there commands us to love. Consequently, there are two parts to the Commandment:

1. First, that we should not harass, oppress, or be at enmity with anyone.
2. Secondly, that we should not only live at peace with people, without stirring up quarrels, but also should aid, as far as we are able, the afflicted who are unjustly oppressed, and should endeavor to resist the wicked, so that they may not injure people as they please.

Christ, therefore, in explaining the true meaning of the Law, pronounces as transgressors not only those who have committed murder, but also declares that

“he shall be in danger of the judgment who is angry with his brother without a cause; and whosoever shall say to his brother, Raca, shall be in danger of the council; but whosoever shall say, Thou fool, shall be in danger of hell-fire” (Matthew 5:22).

For He does not there, as some have ignorantly supposed, frame a new law, as if to cast blame upon His Father. Instead, He shows the folly and perversity of those interpreters of the Law who only insist on the external appearance and outer shell of things, as is commonly said, since the doctrine of God must rather be evaluated based on proper consideration of His nature. Before earthly judges, if someone has carried a weapon for the purpose of killing another person, he is found guilty of violence; and God, who is a spiritual Lawgiver, goes even further.

With Him, therefore, anger is considered murder. Indeed, since He penetrates even the most secret feelings, He considers even concealed hatred to be murder. For this is how we must understand John’s words, “Whosoever hateth his brother is a murderer” (1 John 3:15); that is, hatred conceived in the heart is sufficient for his condemnation, even if it does not openly appear.