Deuteronomy 21: 11

Deuteronomy 21: 11

...and you see among the captives a beautiful woman, and you desire to take her to be your wife,

Why did God ask the Israelites to kill all the people in the seven tribes of Canaan, but then allowed them to take other captive women as wives?
We must understand that the Old Testament deals with two different kinds of enemies. First, the seven tribes of Canaanites represent evil spirits and those who give themselves completely to the possession of evil spirits. They are the enemies of God. These people were to be totally extinguished.
Other groups of people, including the Moabites, the Ammonites, the Edomites, and the Midianites, were all instigated by Satan to fight against Israel. God clearly asked the Israelites to take a detour to avoid fighting with the Moabites and the Ammonites, since God gave these lands to the descendants of Lot. But they attacked Israel anyway, so God eventually punished them.
Today we also have two different types of spiritual enemies. First, we have evil spirits, which we must resist. The Bible says that if we resist Satan, he will flee from us. There is no negotiation in this area. We must conquer them.
Second, we have our flesh. We must deal with the flesh through Christ’s work on the cross. Sometimes, it takes time and detours to deal with the flesh.
We must remember this difference when we confront conflicts in today’s church. If we hate our brothers who are behaving in a fleshly way and try to “kill” them, we are in trouble. We must have patience and grace in dealing with the flesh when it shows up in our lives and in others’ lives.