Why should the people of Deuteronomy do what God says? Throughout Deuteronomy, God calls his people to obedience by repeating a specific phrase as seen below:
Walk in obedience to all that the LORD your God has commanded you, so that you may live and prosper and prolong your days in the land that you will possess. Deuteronomy 5:33
God encourages his people to obey so that they will live and prosper in the promised land. There are two reasons I believe this is the case. The first is that they will thrive because their obedience draws them closer to God, who will not let them go.
The second reason is that God is most informed on how to live in this world. When a parent instructs a child, they come from a position of understanding how the world works. The parent knows how things work, while the child who listens in obedience does not. A good example is when one tells a child not to stick a knife in a toaster. The parent understands the consequences of doing such action and instructs the child not to. An obedient child listens even if they have no understanding of why.
When the creator of the universe calls his people to obey him, he calls them from an informed position about how the world he created works. The word of God and obedience to it is good for us as it allows us to live life the way our creator intended. Today as we look to our calling to follow Jesus, we are encouraged to see the real wisdom of God and how we are to live in this world. Fortunately for us now, we know that we have his Spirit to guide us, a Spirit that will never leave us.