This is a story that on first read seems a lot less important for us than for the people who experienced this event. God tells Joshua right at the beginning what's going to happen and why -- the miracle will confirm for the people that God is with him, as God was with Moses. Especially because the miracle will be very similar to the one that God worked at the Red Sea, where the Israelites also crossed a body of water on dry land.
That's pretty important for Joshua and for the Israelites. We're used to government that functions more or less the same during and after a transition in leadership. A new governor or a new president may (or may not) take things in new directions, but we know that the machinery of everyday government will keep things running. The Israelites' culture offered no such assurances -- how could they know if Joshua was up to snuff? How could they know if he could lead the people? How could they know if their new leader would walk the path laid out by the Lord or if he would take his followers away from God onto some unfortunate path? When the Jordan River stopped flowing and the people walked across it on dry land, that confirmed for them that God was with Joshua as he had been with Moses.
You and I, though, should we need to cross the Jordan River, would probably use a bridge or a boat. We wouldn't need the water to stop flowing, because we have other ways to navigate than just our own muscle power. We also may not be too concerned over who's in charge of the ancient Israelites, since it's not us. So can we learn something from this part of Israel's history?
I think we can, but we have to read it carefully. The quick version might say that Moses parted the Red Sea, Joshua parted the Jordan River; so Joshua is just as good a leader as Moses. But that's wrong.
At the Red Sea, Moses did indeed stretch out his staff against the waters. But it was the wind that blew and created the path for the escaping Hebrews, and a powerful wind was very often seen as a sign of God's presence -- just as it had been in the story of creation in Genesis. And the Jordan didn't stop flowing when Joshua crossed it, but when the feet of the priests carrying the Ark of the Covenant touched the water. Again, the Ark symbolized the presence of God in a special way, and so both times the people saw God at work on their behalf, demonstrating to them that the person leading them was following a path God laid out.
In fact, the people of Israel had the most trouble when they took their eyes off the idea that God led them and relied too much on their human leaders. When Moses was up on the mountain receiving the Ten Commandments, they worried because he had been gone so long, and they asked Aaron to make them the golden calf as their god. You know what was going on around them when they asked for this? The top of Mt. Sinai was covered in a storm, a symbol of God's direct presence while he spoke with Moses. Reminders of God's care for them were all around them, but because their focus on their human leader and his absence prevented them from seeing those signs and realizing their true leader was still with them.
We can idolize people just as easily as they did. Large churches with charismatic leaders may struggle when those leaders move on, even if the changeover happens without some kind of scandal. People who found their church a place to encounter God, to meet to worship him and to enable them to do his work for people in need will miss their old pastor, but they will continue. People who came to the church because of the pastor's top sermons or because of the prestige of attending that pastor's particular church will have a harder time and may not stay.
We can idolize many other aspects of church -- worship styles, emotional experiences, other people with whom we attend -- and forget that our main focus in our church life needs to be God. Just as we might attend a church because we feel good about one or another of those things, we might not attend because we feel bad about them. We've always gone to a certain church, but now we're mad at the pastor so we'll go somewhere else. The church hasn't been doing enough of the kind of music we like, so we'll go to another one. Or we'll sit through worship and grump about it and how much better it used to be, which may make our pastor wish we would move on to another church.
The key mistake we all make is attaching our loyalty or our reverence to something that isn't God, when the purpose of church is worship of God. The key mistake the Israelites made with Moses was attaching their allegiance to him instead of to God, and Joshua points out clearly that the miraculous work at the river is not his doing but God's. It may confirm him as God's chosen man, but God remains the true leader of the people. The people may follow Joshua now because they know he follows God, but if he should ever stray from that they should drop him like a bad habit.
Which, come to think of it, isn't only a metaphor in this case.