The great captain of Israel, Joshua, died while canaanites devoted to destruction still dwelt in the promised land. The children of Israel failed to destroy them as they had been commanded: indeed, after the death of Joshua and the generation that had originally invaded the land, they made alliances with these pagans and served their gods. Matthew Henry has a stimulating comment about this.
Though our Lord Jesus spoiled principalities and powers, we see not yet all things put under him; there are remains of Satan’s interest in the church, as there were of the canaanites in the land; but our Joshua lives for ever, and will in the great day perfect his conquests.
Joshua did not finish the work of exterminating the enemies of God’s people because he died. But Christ does not die, and will do His work perfectly. As Hebrews 7:25, speaking of the unchangeable priesthood of Christ says: Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.