The writer of the epistle to the Hebrews said, “by so much more Jesus has become a surety of a better covenant.” (Heb 7:22) This better covenant is the new covenant, compared to the old one. What makes the new covenant better than the old covenant?
Firstly, the new covenant was established on better promises than those of the old covenant (Heb 8:6). What are these better promises? God will put His laws in the mind of His people and write them on their hearts; and He will be their God, and they shall be His people. And, none of them shall teach his neighbor, and none his brother, saying, ‘Know the Lord,’ for all shall know Him, from the least of them to the greatest of them. For God will be merciful to their unrighteousness, and their sins and their lawless deeds He will remember no more.(Heb 8:10-12)
Secondly, in the new covenant, the surety of the promises is not based on the obedience of the people of God, but on the obedience of the Son of God, Jesus. That is not how it worked in the old covenant. In the old covenant, the surety of the promises was based on the obedience of God’s people. If they obeyed, then they received the promises. But, if they did not obey, then they could not receive the promises. In the new covenant, the surety of the promises is no longer based on the obedience of God’s people, but on the name of Jesus, because He has obeyed. Though the people do not obey, they can still receive the promises because the surety of the new covenant is not them, but Jesus; is not in themselves, but in Christ Jesus.