Take note of this command and the promise in our reading today. Later on, when the people are faced with the task of conquering the Promised Land, they will grow fearful and they will balk at the thought of going to war against the people of the land. But here, very early on, God gives them the promise that He will be the One who will drive out these people before Israel and He will give His people the victory. They need only trust Him and all will be well. But they didn’t trust the Lord and they didn’t rely on His promises when the moment of trust came. When the 12 spies returned from spying out the land they declared that there is no way that Israel could hope to win the day. But they were ignoring the promises of God!
Furthermore, later on, after the people have indeed, through lack of faith, failed to drive out all the inhabitants of the land, they did indeed begin to interact with this people and intermarry with them. And they were indeed led into worshipping other gods, even as God had warned them would happen if they did not stand firm in their faith and do what God had called them to do. They had forgotten the promise as well as the warning.
We believers live upon the promises of God. We have joined ourselves to the Lord and He has made promises to us. And we live out our days making decisions, choices and forming our values based on what God has promised. Most people make choices based on their desires or their fears, or both. But we follow the path dictated by the promises of God.