Hebrews 7:1-14 (ESV)
For this Melchizedek, king of Salem, priest of the Most High God, met Abraham returning from the slaughter of the kings and blessed him,  and to him Abraham apportioned a tenth part of everything. He is first, by translation of his name, king of righ teousness, and then he is also king of Salem, that is, king of peace.  He is without father or mother or genealogy, having neither beginning of days nor end of life, but resembling the Son of God he continues a priest forever.
 See how great this man was to whom Abraham the patriarch gave a tenth of the spoils!  And those descendants of Levi who receive the priestly office have a commandment in the law to take tithes from the people, that is, from their brothers, though these also are descended from Abraham.  But this man who does not have his descent from them received tithes from Abraham and blessed him who had the promises.  It is beyond dispute that the inferior is blessed by the superior.  In the one case tithes are received by mortal men, but in the other case, by one of whom it is testified that he lives.  One might even say that Levi himself, who receives tithes, paid tithes through Abraham,  for he was still in the loins of his ancestor when Melchizedek met him.
 Now if perfection had been attainable through the Levitical priesthood (for under it the people received the law), what further need would there have been for another priest to arise after the order of Melchizedek, rather than one named after the order of Aaron?  For when there is a change in the priesthood, there is necessarily a change in the law as well.  For the one of whom these things are spoken belonged to another tribe, from which no one has ever served at the altar.  For it is evident that our Lord was descended from Judah, and in connection with that tribe Moses said nothing about priests.
Melchizedek. He has been a conundrum for a very long time. In typical fashion students of the Scriptures and their teachers have busied themselves with questions about Melchizedek that the writer to the Hebrews does not address. I cannot bring myself to try to deal with them in personal or public study. We simply note this from the text before us.
1) Jesus is a priest after the order of Melchizedek (6:20). This means, at the very least, that Jesus is not a Levitical priest. He is not a priest according to the Law of Moses, because as a member of the tribe of Judah Jesus does not qualify for the Levitical priesthood. The point being made here is that to be a priest according to Melchizedek is to be a priest of a higher order than the Aaronic priesthood. This is stated in 7:9-10.
2) He was greater than Abraham, for Abraham received a blessing from him (verse 1) and the one who blesses is greater then the one who gets blessed (verse 7). Jesus is greater than Abraham. Jesus blesses Abraham.
3) Abraham gave him tithes of his spoil from his fight with Chedorlaomer, King of Edom (Genesis 14:1-20). Again, the point is that in order for Melchizedek to receive tithes from Abraham he must be greater than Abraham. Jesus is greater than Abraham and deserves tithes and more.
4) Melchizedek has no genealogy listed and therefore has no father or mother mentioned. Jesus has no father or mother either in that He is eternal and created the very one who gave Him birth.
5) Because of his lack of genealogy Melchizedek has no record of beginning or ending and therefore resembles the Son of God. Jesus too has no beginning or ending but it is because he had no beginning or ending and He is the Son of God (verse 3).
6) When Abraham gave tithes to Melchizedek it is as if the tribe of Levi was doing it because the tribe of Levi was yet to be born and can be said to be residing in the one who offered the tithes. Therefore Melchizedek is greater than Levi and as Jesus is a Melchizedek priest He is greater than Levi as well (verses 4-10).
It all boils down to this. To these Jewish believers who are being tempted to return to the Law of Moses the author tells them that they should not do that because the priesthood of the Law of Moses bows to Jesus Christ. That system is gone – forever. Jesus has come and He alone is worthy of our devotion.
Gentile believers today are not tempted to return to the Law of Moses and the levitical priesthood. But we are all tempted to give our allegiance to things or people who owe their allegiance to Christ. Forsake nothing for Christ. He is Lord of all.
Examine your heart to see if your loyalties are divided in any measure whatsoever. If so, that is idolatry and it is foolish. It is idolatry because we worship what has first place in our hearts. It is foolish because to leave the greater for the lesser, the permanent for the temporary is just plain stupid. Don’t be stupid. Stick with Christ.