Just as Jesus used everyday examples to teach, Paul does the same thing here. Everyone who had ever made a purchase of home or land, easily understood that once the transaction had been completed and witnessed, it became a legal contract. While contracts and covenants are both legal and binding, the big difference in the two is this; A contract is valid only as long as both parties do what they have bound themselves to do while a covenant is binding on one party even if the other party fails to keep their end of the deal. So, since God knew man would not keep up his end, He made a covenant that bound Him regardless of what man did. Once God made the covenant promises to Abraham, God was bound by His own word to keep it forever. Nothing man did or does or will do can change God’s plan. He was faithful to Israel even though they failed Him time after time. The new covenant is not a change in God’s plan, it was decided on long before the foundations of the world were laid. Under the new covenant, God is faithful to all who receive Jesus as Savior, even though, we, like Israel fail Him time after time, He is bound by His own Word to remain faithful to us.
“The Gospel has come to you because it’s on its way to someone else.” -Anonymous