The Midianites, in cahoots with the Moabites, wanted Balaam the prophet to curse Israel so they could drive the Israelites out of the region. He was unable to do so because, as he said, he could not curse those whom the Lord has not cursed. But before he went back home from his audience with the Moabite king and with the Moabite and Midianite officials, he advised them to have their women seduce the Israelite men into idolatry by luring them into sexual immorality. Balaam hoped this would lead to the Israelites losing the favor of God, thereby losing God's protection. The men who hired Balaam refused to pay him after he was unable to curse the Israelites, but perhaps he hoped if his proposed scheme worked they would call him back to reward him.
The scheme was successful on a percentage of Israelite men: 24,000 of them died as a result of their immoral interactions with the pagan women. But Israel still has over 600,000 men able to serve in the army and the Lord is angry on behalf of Israel that the heathen people of the region have made themselves her enemy without cause and have plotted for her downfall. He is going to avenge Israel and He is going to invite the Israelite army to take part in the vengeance.
There are many instances in the Bible where the Lord avenges Israel or a citizen of Israel all by Himself; He does not ask or expect the person or the nation to lift a finger. After all, He says, "Vengeance is Mine; I will repay." (Deuteronomy 32:35) But in some cases the Lord invites the person or nation to take part in the process alongside Him. This type of participation can only happen if the Lord makes the invitation. To take such a duty upon oneself would be wrong, as the Apostle Paul instructed the Christian church when reminding the church of the Lord's words from Deuteronomy 32:35: "Do not take revenge, my dear friends, but leave room for God's wrath, for it is written: 'It is Mine to avenge; I will repay,' says the Lord." (Romans 12:19) In Numbers 31 we find one of the instances in which the Lord invites Israel's army to take part in the vengeance He intends to pour out on the enemy.
The words "Midianite" and "Moabite" are sometimes used interchangeably because they were neighbors who mingled with each other in public and in private. They were allies in government. They were partners in business. They intermarried with each other. So in a sense they were almost one people. In another sense they were not because the Moabites were descended from Abraham's nephew Lot and the Lord will tell Israel that He has not given them the territory of the Moabites in the promised land, and this is due to the Moabite's ancestral kinship to the Israelites. (Deuteronomy 2:9)
Chapter 31 deals with the Lord's punishment upon the Midianites for their part in the scheme to bring about Israel's downfall. The Midianites will disappear entirely from the pages of the Bible in the book of Judges whereas the Moabites will continue to be mentioned up through the book of Isaiah.
"The Lord said to Moses, 'Take vengeance on the Midianites for the Israelites. After that, you will be gathered to your people.'" (Numbers 31:1-2) Moses has already been informed that he will not enter the promised land. The time of his departure from this earth is approaching but he will not die immediately after the defeat of the Midianites. I don't think that's what the Lord is saying. I believe the Lord's words could be taken like this, "You will see this enemy defeated in battle before I call you home". Moses will still have matters to wrap up after the battle with the Midianites and I think the reason the Lord says what He says in verses 1 and 2 is because Moses' anger burns hotly toward the Midianites for the havoc they wreaked upon his people. Moses is justifiably angry and it's not sinful for him to want to see the Midianites punished. He lost 24,000 of his fellow citizens due to the wickedness of these pagan people. I've been angry on behalf of people I love. I've wanted to see the Lord discipline people who have been wicked toward those I love. I am sure you have found yourselves feeling the same way when someone has mistreated one of your family members or friends. I think Moses is angry on behalf of the people he loves. Before he dies he deeply desires to see the wrath of God fall upon the Midianites. It could be that he's prayed to the Lord to see such a thing before he leaves this world. Or it could be that the Lord just knows this is what is in Moses' heart since the Lord knows everything that is in everyone's heart. I think verses 1 and 2 are to be taken as reassurance---as the Lord promising Moses the same thing He will promise King David centuries later: that He will allow him to see his desire upon his enemies. (Psalm 59:10, Psalm 92:11)
I imagine the Lord's words are very comforting to Moses. I am not sure Moses could have gone to his death with a restful spirit if the Lord had not allowed him to see the Midianites defeated in battle. Moses won't die until Deuteronomy 34 but the last thing he will say to the people of Israel will be words of assurance that the Lord will always avenge them on their enemies. By that time He will have avenged them upon the Midianites, but many battles will still be ahead. Many tribes and nations will come against Israel in the coming years and even up until our own day and beyond. But the Lord's promise to curse those who curse Israel still stands. No one can make themselves an enemy of Israel and get away with it, and the last words from Moses' mouth to the Israelites will contain the promise of the Lord that He will "avenge the blood of His servants" and that He will "take vengeance on His enemies and make atonement for His land and people". (Deuteronomy 32:43)
Join us tomorrow as we begin our look at the battle between the Israelites and the Midianites.