Ephesians 2:12 That you were at that time apart from Christ, alienated from the commonwealth of Israel, and strangers to the covenants of the promise, having no hope and without God in the world. Matthew 26:28 For this is My blood of the covenant, which is being poured out for many for the forgiveness of sins .
According to verse 12, we were also “strangers from the covenants of the promise.” God's covenants are His promises. His promise is His word that He will freely do certain things for His chosen people. Such a word of promise is not a demand, a requirement, or a rebuke.
The basic thought regarding God's promise is that it is His word. Apart from the word, there is no promise. Eventually, God's promise became the binding covenant because it had been legalized by the necessary procedures.
Both in the Old Testament and the New Testament God's words of promise have been legalized to become a binding covenant [testament]. You may wonder what procedure was necessary to legalize God's promise into a covenant. The best illustration concerns the death of the Lord Jesus for the forgiveness of our sins.
The Lord promised that He would shed His blood on the cross so that we might receive the forgiveness of sins. The promise of forgiveness was legalized by the shedding of His blood. Through this procedure, His promise became a covenant.
No promise binds a person as much as a covenant does. Men can make promises without being bound very much by them. But once we pay the price for that promise to become a covenant, we are bound by the covenant we have made.
The price is the procedure necessary to make the promise a covenant.