The Law of Moses also says to execute gays, adulterers and those who work on weekends.
No death penalty in the New Covenant.
Matthew 5:21 "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:' "
Jesus is getting right down to the basic law with us, Then He states the sixth commandment from Exodus 20:13; "thou shalt not kill." This law is taken out of context, and is becoming a lie as presented in the modern world today. We see the good reverends going out to burn the candles at the executions of murders, and displaying their stupidity of God's Word before the world. If they took a little time to understand the true meaning and intent of God's Word, they would know that as it is translated in the King James, it is incorrect. It is a false statement even, for it is incomplete.
Lets go to Strong's Hebrew Dictionary, # 7523; "Ratsach, raw-tsakh'; a prime root; to dash to pieces, kill a human being, especially to murder, to put to death, (man) slayer, murder (er).
In the Strong's Greek dictionary it is # 5407, "Phoneuo, fon-yoo'-o; from # 5406, to be a murderer (of), kill, do murder, slay." So lets go to # 5406, "Phoneus, fon-yooce' , A murderer, (always a criminal act [at least initial] homicide, 5407 is the term for a public bandit, 5406 is term for murderer."
When we go back and read the sixth commandment again, for what it really says, we see a totally different meaning. Christ has just told us that the law hasn't changed. The law doesn't say, "Ye shall not kill", it states "thou shall do no murder, criminal homicide", and that is the criminal intent beforehand to take a man's life. There is a great difference. "And whosoever shall commit criminal homicide murder shall be in danger of the judgment.
God's law spells out the righteous way of dealing with murderers, without a just cause, and this is addressed in Numbers 35:17-21, "The revenger of blood himself shall slay the murderer: when he meeteth him, he shall slay him." The revenger is the next of kin, and by this righteous act of killing the murderer on the spot, the community will be free of them, "and others will see and these things will cease happening." When blood is shed, it is the innocent blood that we should be concerned with, not the murderer.
Jesus is telling us that if you murder, He will judge you.