What is sin?
It is the glory of God not honored.
The holiness of God not reverenced.
The greatness of God not admired.
The power of God not praised.
The truth of God not sought.
The wisdom of God not esteemed.
The beauty of God not treasured.
The goodness of God not savored.
The faithfulness of God not trusted.
The commandments of God not obeyed.
The justice of God not respected.
The wrath of God not feared.
The grace of God not cherished.
The presence of God not prized.
The person of God not loved.
That is sin.
― John Piper
Think about this verse from 2 Corinthians 5:17 (ESV), "For our sake he made him [Jesus] to be sin who knew no sin, so that in him we might become the righteousness of God."
All of those statements that are quoted above by John Piper, God punished the sin of those things that we have committed against God, who did not deserve to receive such, but we did.
THIS is what makes the cross Good News to tell others about!