Joshua 3:10 And Joshua said, Hereby ye shall know that the living God is among you, and that he will without fail drive out from before you the Canaanites, and the Hittites, and the Hivites, and the Perizzites, and the Girgashites, and the Amorites, and the Jebusites.
God is among you, He is giving you the Land, and He is driving out the pagan enemies, All this is by God’s grace as a gift, and He is doing it all by His working. You just need to receive it by faith. By the crossing of the Jordan God says you will respond by knowing that the Living God is among you to keep His promises. This knowing will be necessary for the people to have the faith to believe God and the courage to do what He says.
This is written for our learning. God gives the kingdom. We enter it by being born again through Baptism and the Word. The spiritual enemies that oppose our entry into and enjoyment of God’s Life are driven out by the suffering, death, and resurrection of Jesus Christ. The Spirit grants us faith to believe Jesus. Now we know. It is vital for us to have this knowing when dealing with the problems of life. We follow our Joshua (Jesus) into battle and conquer the seven nations (the “-ites”) that are in the way. It is not easy, but we know He is with us.
For the daily battles we need reminders. God gives reminders in the Gospel, in the remembrances of Baptism, and in the Lord’s Supper. Just like Joshua set up a memorial of stones as a reminder forever, so the Word and the Sacraments remind us regularly. By these means we know God is among us.