I've recently studied through Joshua, thanks to Search the Scriptures (highly recommended by the way). Today, as the last day in the book, was a 'revision' time of looking back over the book and seeing the big lessons. There are many, but I just wanted to write about one particular theme that has helped and challenged me.
People often puzzle over the relationship between God's sovereignty and our responsibility. God is not a passive God, but neither are we his puppets. How does this work in practice, and what does it mean for our lives? Joshua, I think, presents a very clear picture of how this works itself out. It doesn't give us textbook answers but it shows us what it looks like.
God gives the land to Israel
Chapter 1:2-4, Chapter 2:9, Chapter 6:2, etc. etc. The Israelites do not conquer the land in their own strength - God gives it into their hand. Even though they are a small people with no cities of their own, the other nations 'melt away' before them in terror because they know that God is with them. Likewise, our salvation is God's work. We cannot rescue ourselves from our sin-induced death (Ephesians 2:1,5). God's sovereignty and power is unquestionable.
Israel had to take action and work hard
Yet although God's grace gives us these blessings, that does not mean that we are to relax and be passive. The Israelites had to fight to take possession of the land that God had given them. This is clearly seen in Chapter 10, where Joshua and all Israel fight city after city in Canaan. But why do they have success? Verse 42: 'And Joshua captured all these kings and their land at one time because the LORD God of Israel fought for Israel'. God's sovereignty worked out through our responsibility. Later on, even when the tribes are receiving their inheritance, the people of Dan have to fight against Leshem for the land. What does this mean to us? Even though we have been saved and the Holy Spirit is now living in us, we must fight the sin that is within. Each city the Israelites conquered is echoed by a sinful habit that we must purge, through God's grace and his Spirit. In short, we must 'work out our salvation with fear and trembling, for it is God works in us, both to will and to work for his good pleasure' (Philippians 2:12-13).
Maybe that doesn't make the technicalities of this theology any clearer. I don't think we can ever understand just how God's power and our responsibility co-exist. But Joshua shows us how it looks. We need to be ruthless with the sin inside us, just as Israel had to be ruthless in purging the land of idolotrous nations. The reason we can do this at all is because God enables us to, but we need to be strong and courageous in this knowledge and get on with it!