Whoever hates his brother is a murderer, and you know that no murderer has eternal life abiding in him.
Listen to the "Verse by Verse" episode covering this scripture.
As Jesus Christ showed in His Sermon on the Mount, the spiritual intent of the 10 Commandments involves our thoughts and attitudes. So the spirit of hate is the attitude that can lead to the physical act of murder.
Those who follow Jesus Christ’s example obey God’s commandments in the letter and the spirit. Those who break the law in the letter or the spirit without repentance will not receive the gift of eternal life.
For more about the spiritual intent of the law against murder, see “Jesus Christ Taught Peace and Nonviolence.”