Antagonists of the Bible delight in pointing out the contradiction between this command and other biblical laws. God prescribes through Moses the death penalty for adultery, bestiality, incest, homosexuality, kidnapping, cursing one’s parents and murder. Since the fall of Adam and Eve animals have been sacrificed as an act of righteousness.
This law first appears in Genesis 9:6 when God commanded Noah “Whoever sheds human blood, by humans shall their blood be shed; for in the image of God has God made mankind.” This verse by itself presents a logical dilemma or contradiction. Its obvious implication is that there are cases where the killing of a person is lawful. The biblical narrative excludes accidents, war, [self-]defence and capital punishment from the definition of murder.
Exodus 20:13’s “kill” from the King James Version is modernly translated as “murder”. While the King James Bible is a wonderful literary work, I recommend against it for serious biblical studies/analysis. It is translated from Latin, from Greek from Hebrew; and is easily misunderstood by modern readers. The English language has since diverged to the extent that some words now mean the opposite. Modern translations source much older manuscripts such as the pre-christian dead sea scrolls to provide a more accurate translation from the original languages. In spite of this the narratives are identical, disproving antagonist’s claims of rife corruption as popularized by Islam’s Mohammed. This severely refutes accusations of Christians rewriting history to suit their fabrications.
Bible students are taught to establish doctrine based on multiple verses and without other contradiction. This avoids problems such as this where old English mis-translates the Hebrew word רָצַח (ratsach), which means slay or murder.
I think the subconscious concern about all this God-ordered death is the implication of our own impending judgement, and we know we’re as guilty as the next person. This is why Jesus’ message is called the good news. Jesus’ work resolves God’s dilemma that we cannot enter his presence because of our guilt. Whoever believes in him will not perish but have everlasting life John 3:16. And in this life, we are empowered to overcome our naturally sinful tendencies – not that we get that perfect though. Jesus came to fulfill the law, not to do away with it. The biblical law is still applicable. It serves to describe God’s will and warn us of our consequences. But Christians are called to forgive as we have been forgiven. Jesus did not come to judge, so neither should we. However he will return to judge. Now is an amnesty of grace.