Num 31:14And Moses was wroth with the officers of the host, with the captains over thousands, and captains over hundreds, which came from the battle. 15And Moses said unto them, Have ye saved all the women alive?
16Behold, these caused the children of Israel, through the counsel of Balaam, to commit trespass against the LORD in the matter of Peor, and there was a plague among the congregation of the LORD. 17Now therefore kill every male among the little ones, and kill every woman that hath known man by lying with him. 18But all the women children, that have not known a man by lying with him, keep alive for yourselves.
The Israelites did not want to kill the Midianite women who had previously seduced them to fornication and the Lord judged them and killed many of them. They secretly hoped they could preserve them and turn them into "semi-legal" concubines. Moses was right in demanding them to be killed. They would have seduced the Israelites again just as Solomon was drawn away by foreign women. Israel would have utterly been defeated and God's purposes thwarted.
This is one of the most difficult passages in the bible to accept. There is no more killing of people ordained in the New Covenant, but we must kill our desire for Midianite women that represent lust. We must be ruthless in our struggle against our lust. Either we kill it, or it kill us. The two cannot coexist. We will either overcome or be overcome.
This causes some suffering, but the end of it will be glorious!
Heb 12:4 Ye have not yet resisted unto blood, striving against sin.
1 Peter 4: 1Forasmuch then as Christ hath suffered for us in the flesh, arm yourselves likewise with the same mind: for he that hath suffered in the flesh hath ceased from sin; 2That he no longer should live the rest of his time in the flesh to the lusts of men, but to the will of God.