From the original promise to Abraham, the Israelites had cherished for over 400 years the Word that said God would bring them into the Promised Land. The land the Gadites and Reubenites wanted to claim was on the threshold of that promise.
Instead of pressing on, being faithful to God's calling and pursuing His promise, they wanted to settle for what they could see and hold today. I hope that strikes home with you as hard as it does for me. How often am I content with where I am and unwilling to go the extra mile toward what God has promised? I Timothy 6:6 tells us "Now godliness combined with contentment brings great profit." But there is an immense difference between being content with where God has you for a season, and being content to remain in that place rather than press on toward God's best for you.
Moses chastises them with the warning that their complacency could discourage their brothers and sisters. He warns them that the same unwillingness to follow God wholeheartedly caused the Israelites to wander for 40 years in the wilderness and cost that entire generation, save Joshua and Caleb, the opportunity to enter the Promised Land. I wonder if Moses was especially sensitive because the incident which cost him a home in the Promised Land occurred after they had turned back because of the discouragement of the spies. Their complacency personally cost him the Promised Land.
Our complacency may cost us the blessings God promised.
The Israelites complained time after time, "If only we could go back to Egypt . . . ." Are we crying out, "If only we could go back to a simpler time!" But for whom was it a simpler time? Was it really a simpler time when our brothers and sisters had to have a guide to show them where they might travel safely within our country -- THEIR country? http://library.sc.edu/digital/collections/greenbook.html
God's promise to our nation is the creed that was given to our founding fathers. "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the Pursuit of Happiness. That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed."
Our forefathers didn't grasp the full breadth of this promise. They didn't understand that it applied to the natives of the land that they were dispossessing and committing genocide against. They didn't recognize that it applied to the Africans that they were importing and enslaving. And they didn't realize that it applied to "mankind" and not only men.
We understand that now -- at least most of us do. We can't be complacent and settle for the status quo where we have not yet entered the Promised Land. We all miss out on the blessing of God when we settle for what we have today instead of marching forward, united with our brothers and sisters.