The end of Hebrews 4 informs us that Jesus is our Great High Priest and then the chapter ends. Hebrews 5 tells us why he is a better high priest than the Levitical priests of the Old Covenant. The high priests called by God to the priesthood were human beings and had the same shortcomings as the people they ministered to. They had their own sins to confess and be forgiven before they could attend to the sins of others. The Christ is God’s own Son and also a priest forever after the order Melchizedek. Abraham was blessed by Melchizedek in Genesis 14 and Abraham gives him a tenth of everything he has. This is centuries before the Law was given to Moses. The Levitical priesthood had not been established and there was no commandment, at least none recorded, to give a tithe. Genesis will not answer all of our questions. There is no recorded beginning nor ending of Melchizedek’s priesthood and this little detail is used to show what kind of high priest Jesus will be. There is no beginning and no end to his priesthood. He does not have his own sins to sacrifice for, and he is not called by God but is God’s own Son. Although he was the only begotten Son, through suffering in his mortal flesh he learned obedience.
The final verses of chapter 5 is a chastisement to an audience that should be eating “spiritual food” as mature believers but must still be given milk as infants. Hebrews will get to comparing Jesus to Melchizedek in a couple of chapters and list more ways in which he is greater.