Hebrews 7:21-25
Heb 7:21 (KJB)
(For those priests were made without an oath; but this with an oath by him that said unto him, The Lord sware and will not repent, Thou art a priest for ever after the order of Melchisedec:)
(Psa 110:4 KJV) The LORD hath sworn, and will not repent, Thou art a priest for ever after the order of Melchizedek. The writer has chosen to quote many times from Psalm 110:4 which shows how impossible it is to exhaust the truths in the word of God. The Levitical priests and those in the order of Aaron were not installed with oaths. They were no doubt installed because of lineage but the Lord Jesus Christ was installed as High Priest for all the believers by an oath, which we previously saw that God had sworn by Himself. This oath was for the eternal priesthood of the Lord Jesus Christ and it will never be revoked.
Heb 7:22 (KJB)
By so much was Jesus made a surety of a better testament.
Surety - Guarantee or pledge
Of a better - Superior
Testament - Covenant
Here the identity of the High priest is made known, although we knew who it was already. By the sacrifice of Jesus for His people, He has become a surety of a more superior covenant. This means that this new covenant carries with it many guarantees and Christ stands behind those guarantees. Those guarantees are eternal life for those who believe, He makes intercession for His people, they can never lose their salvation, their sins have been nailed to His cross and taken out of the way forever, they have irrevocable peace with God through the better covenant. This is called the second covenant which is the covenant of Grace. There are no more animal sacrifices and no more earthly priests mediating but the Lord Jesus Christ Himself is the final sacrifice for the sins of His people and His High priestly ministry is a continuing one without interruption.
Heb 7:23 (KJB)
And they truly were many priests, because they were not suffered to continue by reason of death:
This verse tells us plainly that throughout the course of the Mosaic law there were many priests who tended the tabernacle and the temple services but each one suffered death and had to be replaced by another in their genealogy.
Heb 7:24 (KJB)
But this man, because he continueth ever, hath an unchangeable priesthood.
Unchangeable - Permanent, without end
In contrast to the earthly priests, the writer is telling us that the Lord Jesus Christ has a priesthood of an eternal nature, according to the order of Melchisedec. This is why He is a mediator of a better covenant because His priesthood is unchangeable in the area of being eternal. Eternal continuity is the very trademark of the High Priestly ministry of the Lord Jesus Christ.
Heb 7:25 (KJB)
Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.
The uttermost - Complete, perfect, or absolute
The writer begins by stating that based upon the previous verses that the Lord Jesus Christ is able to save all those He came to save. The word “uttermost” carries with it the meaning of a salvation which is absolutely complete. In contrast to the Mosaic priesthood where the supplicant would have to come back for every offense and all the males would have to come to Jerusalem and appear before the Lord three times a year. (Exo 23:17 KJV) Three times in the year all thy males shall appear before the Lord GOD. Each year the High priest would also have to go into the Holy Of Holies and make atonement. So that type of salvation was not for the uttermost instead it was not really eternal salvation but to cover their sins so they would not face the earthly wrath of God as we so frequently read in the Pentateuch.
The salvation the Lord Jesus Christ gives is permanent. There will never be need for another sacrifice and those who have become saved have had every single sin they ever committed or would commit already paid for. The believer is totally sinless in their soul even though our flesh still seeks after sin, when a person becomes saved the atonement of Christ is so effectual that there is not one vestige of sin to keep us out of Heaven, as the believer is readied for Heaven as soon as they are saved. We can call it “No Sin Left Behind.” Every sin has been paid for. Not only does the Lord Jesus Christ pay for our sins, but He also intercedes for us at those times when we do sin in the flesh. He intercedes for us as the High Priest did under the Mosaic Law. The High Priest brought the sacrifice and sprinkled blood upon the Mercy Seat of the Ark of the Covenant and that made atonement for Israel. The Lord Jesus Christ is the mercy seat and the Ark of the Covenant and in this way He pronounces complete forgiveness and reconciliation based upon His complete or perfect sacrifice. With the Lord Jesus Christ having a perpetual Priesthood, this means we have no breaks in fellowship with the Father.