In Numbers 25 it is very clear that the leaders of the people were held to account and were punished for the sins committed in Moab.  God had warned the people repeatedly to stay away from the pagan practices of the nations around them. The sins of Israel in Moab started with sexual immorality and led to the worship of other gods. The Israelites allowed the ways of other nations to corrupt them and pull them away from God. Do we as Believers in Jesus allow things and the ways of the world to corrupt us and pull us away from God?

Many of the Israelite men were seduced into idolatry by the Moabite women. It seems as if the Israelite man, Zimri was flaunting the Midianite woman in the presence of Moses and the assembly.  While Phinehas' actions of killing the man and the woman seem harsh to us, he was zealous for God's honor and illustrates the power of ONE. He was rewarded for that. Just an example of rewards to those who wage war against sin. This family will remain as priests. Not only will they remain as priests, but they will be most significant priests.  Zadok and Ezra are descendants of Phinehas. (Ezra 7:1-5)

God’s consequences for this behavior of being seduced into idolatry and flaunting it (as in the case of Zimri) were most severe. Does that tell us something about how much God wants His people to obey Him completely?

I John 5:3
This is love for God: to obey his commands. And his commands are not burdensome,

To show our love for God is to obey His commands. He's told us, it's not that hard!