"The men of Reuben, Gad and the half-tribe of Manasseh crossed over, ready for battle, in front of the Israelites, as Moses had directed them. About forty thousand armed for battle crossed over before the Lord to the plains of Jericho for war." NIV translation
We see that the Israelites crossed over prepared for war to take what God was giving them and we are reminded that we are to do our part here in this world. We have been given authority by Jesus to walk in victory now as well as in the future. We also see that those that had their home on the other side of the Jordan went out ahead to fight for their brothers. This reminds us of the fact that we are to fight for our brothers and sisters. The Israelites had physical battles to look forward to but ours is more a spiritual battle. We struggle against the deception of the devil to show people the truth which is only found in Jesus Christ.
"That day the Lord exalted Joshua in the sight of all Israel; and they stood in awe of him all the days of his life, just as they had stood in awe of Moses." NIV translation
After seeing the favor of the Lord upon Joshua, the people respected him and what God was doing through him.
It is a crucial point to see that it was the Lord that exalted him and not the number of college degrees or certificates that he had. The same is true for us today, in that a true leader is prepared by the Lord and not a course, lecture, or any other man made thing.
"Then the Lord said to Joshua, 'Command the priests carrying the ark of the covenant law to come up out of the Jordan.' So Joshua commanded the priests, 'Come up out of the Jordan.' And the priests came up out of the river carrying the ark of the covenant of the Lord. No sooner had they set their feet on the dry ground than the waters of the Jordan returned to their place and ran at flood stage as before." NIV translation
At his command the priests carried the ark out of the river and the waters went back to flooding. In this, we see the necessity of remaining in the will of God and directed by the power of the Holy Spirit. Our hope, provision and protection from the things of this world are all in Him and where He is. When we choose to do things that are outside of what is best for our lives (outside the will of God), then, we may be flooded with the consequences. We will still be saved for eternity but the effects can make it seem like a hell on earth. The best way to stay in His will is to remember that we are in a spiritual battle. A good soldier for Christ only follows the orders of His Master and doesn't go off on their own.