10. Hereby you shall know, etc He makes the power of the miracle extend further than to the entrance of the land, and deservedly; for merely to open up a passage into a hostile territory, from which there was afterwards no retreat, would have been nothing else than exposure to death. For either entangled among straits, and in an unknown region, they would easily have been destroyed, or they would have perished, worn out by hunger and the absolute want of all things. Joshua therefore declares before hand, that when God would restore the river to its course, it would just be as if he were stretching forth his hand to rout all the inhabitants of the land; and that the manifestation of his power given in the passage of the Jordan, would be a sure presage of the victory which they would obtain over all the nations.
He says, Hence shall you know that the Lord is present with you; to what end? Not only to plant your feet in the land of Canaan, but also to give you full possession of it. For surely when mention is made of the overthrow of the nations, an ultimate, free, and peaceful possession is implied. Therefore, as the Lord by dividing the river clearly showed that his power resided with the Israelites, so the people must on their part have conceived hopes of perpetual assistance, as much as if they had already seen their enemies worsted and lying prostrate before them.
For God does not abandon the work of his hands midway, leaving it maimed and unfinished. (Psalms 138:8) When he leads his people unto the promised inheritance, he makes a dry passage for them by cutting off the course of the Jordan. How perverse then would it have been for the Israelites to stop short at that momentary act, instead of feeling confident in all time to come, until quiet possession of the land were actually obtained! Let us learn then from this example, prudently to combine the different acts of divine goodness relating to our final salvation, so that a happy commencement may cherish and keep alive in our minds the hope of an equally happy termination.
When Joshua says that the people will know the presence of God from the miracle, he indirectly upbraids them with their distrust, as the mere promise of God ought to have sufficed for a full assurance, and our faith, unless founded solely on this promise, must be continually wavering. But although faith ought properly to recline on the truth of God alone, it does not follow that experimental knowledge may not act as a secondary support to its weakness, and give subsidiary aid to its confirmation. For that which God promises to us in word he seals by act, and as often as he exhibits to us manifestations of his grace and might, he intends them to be so many confirmations of what he has spoken, and so many helps tending to suppress all our doubts.