This is about marriage, adultery and Jesus' approach to sin in the context of the woman caught in adultery.
1. The devious hypocrisy of the religious leaders. Whatever Jesus said it would be wrong. The Law specified that both parties in adultery should be killed. Where was the man?
2. The gracious wisdom of Jesus.
3. The radical challenge - go and leave your life of sin. Jesus accepts sinners who repent and leave their life of sin.