Since no one can keep the law, what is its purpose?
That we may know the holy nature and will of God, and the sinful nature and
disobedience of our hearts; and thus our need of a Savior. The law also
teaches and exhorts us to live a life worthy of our Savior.
What is sin?
Sin is rejecting or ignoring God in the world he created, rebelling against
him by living without reference to him, not being or doing what he requires
in his law—resulting in our death and the disintegration of all creation.