You might think, as you read this passage, that the theme today would be the law. When you read the first few verses of Deut. 5, though, you see that Moses is talking about the covenant God made with his people. This covenant was instituted with the giving of the Ten Commandments.
What is a covenant? A covenant is a divine promise that creates and secures a relationship with life or death consequences. The people could not keep the covenant God gave through Moses because of their sin. As it says in Hebrews 8, they did not continue in the covenant to keep it. They were unable to keep it because of their sin, just as we are unable to obey God perfectly.
But God had a plan. Throughout the prophetic books we see God’s intention to establish a new covenant that would supersede the old. The author of Hebrews emphasizes this truth. For by a single offering he has perfected for all time those who are being sanctified (Heb. 10:14). The newness of the new covenant is Jesus. His one sacrifice, replacing the constant sacrifices of the law, brings the forgiveness that the old covenant could never bring. The law and the old covenant point forward to Christ.