Joshua said to the children of Israel, “Come here, and hear the words of Yahweh your God.” Joshua said, “By this [miraculous crossing of the Jordan River] you shall know that the living God is among you, and that he will without fail drive the Canaanite, and the Hittite, and the Hivite, and the Perizzite, and the Girgashite, and the Amorite, and the Jebusite out from before you...” Joshua 3:9,10
It’s important that the impetus for the Jordan-crossing miracle be noted before we even imagine the crossing itself: that, for all time, the Israelites might “know that the living God is among” them, and that, in the coming months and years, “he will without fail drive” the enemy peoples from the Promised Land.
For us, it’s always important that what we’ve seen Him do in the past should be our impetus for believing He can always do all things. Remembrance is an important step in believing. Non-remembrance is the first step toward unbelief.