Heb.7:22 – by the same extent Jesus also has become the guarantee of a better covenant.
Surety is an interesting way of describing the eternal priesthood of Jesus. He is surety to God that we will perform our side of the covenant (because it is Jesus who does it). He is surety to us that the Father will perform His promises because Jesus is the eternal priest Son of God, who is the very outshining and substance of the Father. In the Old Covenant we only had shadows and vague images of God. We had no access to Him to assure us of His promises. In the same way, in our fallen state we could never fulfill the law. No matter how good our intentions were we always fell short. Christ is the guarantee that this arrangement is sure, He has entered behind the veil as our Priest forever. Here is how Andrew Murray describes this passage.
“The surety of a better covenant. It is this Jesus has come to do, to give the covenant its security, and to undertake that its engagements shall indeed be fulfilled. He is surety of the covenant on both sides. Surety to us that God will keep His promise, and give us His life and law and Spirit in our heart; surety to God for us, He will ensure our obedience and our keeping the covenant. Become a Priest with an oath. It is in the priesthood of Jesus that the covenant and the suretyship have their power. It is the Priest for ever who deals with sin and takes it away in the power of an endless life. It is the Priest for ever, the Son of God, perfected for evermore, who has opened a new and living way, a new state of life, and works all in the power of an endless life, in whom we have a divine surety that every promise and every obligation of the better covenant will be fulfilled by God and by us.”
The beauty of this passage is that it is not something we hope for in the future, it is a guarantee that is already in place. The man, Jesus of Nazareth, has entered behind the veil as Son of God and Son of Man. He is already our surety, this life is not only a promise it is a reality for us now.