Also there were many priests, because they were prevented by death from continuing.  (24) But He, because He continues forever, has an unchangeable priesthood.  (25) Therefore He is also able to save to the uttermost those who come to God through Him, since He always lives to make intercession for them.  (26) For such a High Priest was fitting for us, who is holy, harmless, undefiled, separate from sinners, and has become higher than the heavens; (27)  who does not need daily, as those high priests, to offer up sacrifices, first for His own sins and then for the people’s, for this He did once for all when He offered up Himself.  (28) For the law appoints as high priests men who have weakness, but the word of the oath which came after the law, appoints the Son who has been perfected forever.

The unknown author of Hebrews has written this letter to the Jewish Christians to exhort them not to abandon their newly professed faith in Jesus Christ as saviour  in the face of persecution.  In Chapter 7 of this letter, the writer speaks of Jesus as our High Priest and mediator for us with God forever.  He argues the uniqueness of Christ and develops the theme of Jesus as a priest in the line of Melchizedek as being other and also superior to the priests in the line of Aaron (brother of Moses and designated by God as High Priest) and develops this theme for the Jews of his day who knew no other priesthood than the Aaronic.

Melchizedek is mentioned briefly in Genesis.  Abraham, the patriarch of the Jews, was met by the “king of Salem”, Melchizedek,  on his return from defeating the five kings.  Melchizedek was also a priest of God, unrelated to Abraham and who lived hundreds of years before Aaron.    Abraham gave Melchizedek a “tenth of everything” – the spoils of battle – and Melchizedek blessed Abraham.  The situation with the tithing and the giving of a blessing imply that Melchizedek is considered as having superior status to that of Abraham.  This payment of a tithe was also seen as the descendants of Abraham paying it – in the way of speaking in the Bible, the ancestor includes the descendants.

in Psalm 110, God spoke through David about the Melchizedekian priesthood during the time the Aaronic priesthood was established, showing that the priests of the line of Aaron could not accomplish what the priesthood was meant to do.    Priesthood and the law went together so a change in priesthood also meant a change in the law and Jesus did not come from the priestly tribe of Levi but rather the royal line of Judah.  (Both Levi and Judah were sons of Jacob who was known as Israel.)   This Psalm is a prophecy which identifies the Messiah as “a Priest forever According to the order of Melchizedek”.    So the Levitical priests are presented in contrast to Christ.    Christ however is different and superior and remains forever.  Christ has the capacity of bringing a complete salvation to all who approach God through Him.