Exodus 20:13 Thou shalt not kill.
We often tend to think that others commit egregious sins and our sins are small and therefore worthy of grace. But we do not earn grace by being the least of sinners. We receive unmerited grace because we are sinners in great need of that grace. No Christian should be a murderer. We know that murderers do not inherit the kingdom of God. And Jesus reminds us that the murdering mindset is in the heart of all that envy their brothers and harbor hatred in their hearts.
Mathew 5:21-24 Ye have heard that it was said by them of old time, Thou shalt not kill; and whosoever shall kill shall be in danger of the judgment: 22But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, RacaRaca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire. 23Therefore if thou bring thy gift to the altar, and there rememberest that thy brother hath ought against thee; 24Leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift.
We trust that none of you would be so angry and bitter as to actually kill another person. But remember that the anger and hatred that rages in the heart of the murderer began as a flickering flame in the bosom of an ordinary sinner. Do not feed that flame. Do not give yourself reason to stay angry. Do not hold grudges. Do not refuse forgiveness. Do not envy your brothers and sisters in Christ, comparing yourselves one to another. Do not let the sun go down on your anger.
But rather, bless those who curse you. Bless and curse not. Turn the other cheek. Just as you have been forgiven, so also forgive. Resist the devil and he will flee from you. Be reconciled to your brother and then come and offer your gifts to God.