Joshua campaigned against these kings for quite some time. – Joshua 11:18 (NET)
As Israel was taking what it believed to be its promised land and, according to what was believed to be their God’s command upon them, dispossessing the land-corrupting and non-divine-image-bearing nations that were to be found there, it is said that “Joshua conquered the whole land, including the hill country, all the Negev, all the land of Goshen, the lowlands, the Arabah, the hill country of Israel and its lowlands, from Mount Halak on up to Seir, as far as Baal Gaad in the Lebanon Valley below Mount Hermon. He captured all their kings and executed them” (11:16-18). It is these kings of whom it is said, “Joshua campaigned against these kings for quite some time” (11:18).
As one reads about Israel’s conquering and taking of their land of promise, it is necessary to bear in mind what was understood to be the Creator God’s purpose for His covenant people called Israel. Israel, by and large, was to be the Creator God’s instrument for setting the world to rights. To that end, it was they who had received the special revelation of their Lord, so that they might become a light to the nations and to all of creation, so that they might be the reflection of their God’s glory into the world---representing their Creator to creation as had been the intention for the father of their race (Adam). Israel was redeemed (exodused) by their God, from the slavery and exile of Egypt, so that they could be His instruments of redemption and exodus for a world in exile and in bondage to corruption and decay.
Of course, making the natural and logical extension, this can also be said of Jesus, as He was the embodiment of Israel. Extending beyond that, such can also be said of all that would become a part of the Creator God’s covenant people, with this occurring through the believing union with Jesus that is the mark of a trusting allegiance (faith) in Him as Lord. For Israel, because that redemption from slavery and exile from their God’s intentions was for both humankind and the creation itself, the land that they were promised and commanded to occupy can be safely viewed as the first part of the whole creation that was itself to be redeemed. What becomes clear in the Mosaic and historical narratives, is that Israel was to drive all that was representative of evil from the land and occupy it.
Returning to Joshua then, it can be found that “No city made peace with the Israelites (except the Hivites living in Gibeon); they had to conquer all of them” (11:19). Drawing the natural correlation from the responsibility of the Creator God’s covenant people in that day (Israel), with that of the covenant people that are the renewed Israel in Christ (the church,disciples and followers of Jesus), one can here think about that which was penned by the Apostle Paul, in that there would be a constant battle against principalities and powers, against what he refers to as “world rulers of this darkness,” and against spiritual forces (Ephesians 6:12).
Though the believers is never and will never be called to draw swords so as to extend the kingdom of God by violent force, just as Jesus challenged Israel in His day to forsake the idea that the kingdom of God was to be ushered in by bloody overthrow, believers are well able to understand the use of the imagery of battle in the way in which they are employed by Paul. Yes, because of the corruption that entered into the world because of the initial failure to keep covenant, human nature---the nature that had been designed to perfectly bear the divine image and to do that which was pleasing to the Creator God as glory-reflecting stewards of His creation---is itself corrupted.