Luther’s Catechism Questions #60-65
The Fifth Commandment

The Fifth Commandment:
You shall not murder.

What does this mean?
We should fear and love God that we do not hurt or harm our neighbor in his body, but help and befriend him in every bodily need.

Thoughts Vs. Actions
Most people would acknowledge that the fifth Commandment is correct.  It is wrong to murder.  However, our sinful nature bristles at the suggestion that our thoughts and words can make us guilty of breaking this commandment.  But if we hate someone, we wish harm for that person.  We may be pleased if the person were dead.  Thoughts of hatred are murderous thoughts.  Read the story of Cain and Abel, and see how sinful thoughts lead to sinful actions (Genesis 4).