1. Balaam's sin was so despicable (1-3)
Balaam was not a changed man. He knew that divination would not work and so devised another plan. He convinced the women of Moab to entice the Israelites into sexual sin and worship Baal. He knew that this would make God angry and God's hand world be forced to curse his own people (31:16).
2. Some people acted with zeal for the Lord's honor (4-18)
The Lord moved Moses to act. Satan was really working to destroy God's people. They could have melded into the pagan culture. Phineas' response was pleasing to God for the plague stopped. Radical acts of faith are needed at crucial moments. We are called to honor God, love others and obey God with zeal. In these times, our zeal does not atone, but it is pleasing to the Lord.