The central theme of the book of Joshua is that God keeps his promises. Joshua records how God was true to his word in helping Israel take possession of the promised land. What now for them? God does not leave them to carry on in their own strength. Christians, like Joshua, are to be strong and courageous, no matter what we may face - we can be because God is faithful to his promises.
The fulfillment of God’s promises of a land are central to the book. He begins the book with it and brings to closure Joshua’s final charge to Israel’s leaders with it. And the promises of God as fulfilled are found throughout the book.
The truth that God fulfills his promise of a land for Israel also has great implications for the believer today, and that is one of the great applications of the book of Joshua. Those who are truly God’s people shall inherit a land. However, that land is not the dry and dusty land in the Middle East today. Rather, the Apostle Peter tells us that God ‘has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, to an inheritance that is imperishable, undefiled, and unfading, kept in heaven for you’. We as believers have God’s promise of an eternal inheritance and the possession of an eternal land that is real, earthy, and substantial. And, like Israel, we will indeed receive our inheritance because God is a promise-keeper!