Answer
In his first letter, the apostle John makes a startling statement linking hatred to murder: “Everyone who hates his brother is a murderer, and you know that eternal life does not reside in a murderer” (ESV).
The context leading up to John’s statement identifying a hateful person as a murderer is important to study:
For this is the message you heard from the beginning: We should love one another. Do not be like Cain, who belonged to the evil one and murdered his brother. And why did he murder him? Because his own actions were evil and his brother’s were righteous. Do not be surprised, my brothers and sisters, if the world hates you. We know that we have passed from death to life, because we love each other. Anyone who does not love remains in death. Anyone who hates a brother or sister is a murderer, and you know that no murderer has eternal life residing in him. (1 John 3:11–15)
John begins his discussion of love and hatred with a reminder of Jesus’ commandment: “A new command I give you: Love one another. As I have loved you, so you must love one another. By this everyone will know that you are my disciples, if you love one another” (John 13:34–35). According to Jesus (and John), a distinguishing characteristic of followers of Christ is that they love each other—they actively seek one another’s good, even if it requires sacrifice on their part.In 1 John 3:12, John contrasts Christlike love with the hatred Cain showed to his brother (see Genesis 4:1–8). That hatred was based on nothing more than the fact that Abel pursued righteousness and Cain practiced sin. It was hatred that led Cain to murder his brother. Of special note is John’s declaration that Cain “belonged to the evil one” (1 John 3:11). Cain was not a child of God; spiritually speaking, he was a child of the serpent (see Genesis 3:14–15).
Moving from Cain’s story, John reminds his readers that there is nothing new under the sun: “Do not be surprised, my brothers and sisters, if the world hates you” (1 John 3:13). Ever since Genesis, there exists a divide between God’s children and the world. God’s children have passed from death to life; in fact, one of the proofs of their salvation is that they love one another (verse 14). Anyone who does not love God’s children has not yet passed from death to life and therefore “remains in death” (1 John 3:14).
To hate a brother or sister is, in God’s eyes, to commit the sin of murder, just like Cain. And, just like Cain, the hater cannot claim to be a child of God. He has not been born again and has no eternal life (1 John 3:15; cf. Galatians 5:21). The linking of hatred and murder has its origin in Jesus’ Sermon on the Mount, where the Lord taught, “You have heard that it was said to the people long ago, ‘You shall not murder, and anyone who murders will be subject to judgment.’ But I tell you that anyone who is angry with a brother or sister will be subject to judgment” (Matthew 5:21–22).
The proverb advises, “Guard your heart above all else, for it determines the course of your life” (Proverbs 4:23, NLT). Covert sins in the heart, including hatred, are often viewed as less serious than overt, visible sins. But Scripture says that God sees the heart and that all sin is an offense to His holiness. Lust in the heart leads to adultery; hatred in the heart, to murder; coveting in the heart, to theft. Even sin in the heart makes one a sinner.
Jesus loved us enough to lay down His life for us, “and we ought to lay down our lives for our brothers and sisters” (1 John 3:16). A professed follower of Christ who hates his brother or sister is exhibiting the opposite of Christlike, sacrificial love. “Whoever claims to live in him must live as Jesus did” (1 John 2:6).
God is love (1 John 4:8); that is, love is foundational to His nature. If we are truly God’s children, we will have inherited that trait from Him. The apostle John presents this truth as a stark contrast between light and darkness:
Anyone who claims to be in the light but hates a brother or sister is still in the darkness. Anyone who loves their brother and sister lives in the light, and there is nothing in them to make them stumble. But anyone who hates a brother or sister is in the darkness and walks around in the darkness. They do not know where they are going, because the darkness has blinded them. (1 John 2:9–11)
Whoever hates his brother is a murderer because hatred is the root and cause of murder. Believers are called to exhibit God’s love. “Dear friends, let us love one another, for love comes from God. Everyone who loves has been born of God and knows God. Whoever does not love does not know God, because God is love” (1 John 4:7–8).