"The Lord hath sworn, and will not repent, Thou art a priest for ever after the order of Melchizedek" (Psalm 110:4).
The importance of this intriguing verse is indicated both by the fact that it is the central verse of a great Messianic Psalm (quoted at least 12 times in the New Testament) and also because this one verse constitutes one of the main themes of chapters 5-7 of Hebrews, where it is quoted no less than five times (Hebrews 5:6, 10; 6:20; 7:17, 21), and where Melchizedek himself is mentioned nine times. It refers to the fascinating personage glimpsed briefly in Genesis 14:18-20. Melchizedek (meaning "King of Righteousness") is said to have been "King of Salem" (or "Peace"), but there is no record, either in secular history or elsewhere in the Bible, that there ever was such a city or earthly king. He was also called the "priest of the most high God" (Hebrews 7:1), and he suddenly appeared, then disappeared as suddenly as he had come.
Commentators mostly have assumed that Melchizedek was the chieftain of a small settlement of which we have no record, but this hardly does justice to the exalted descriptions of him in Scripture. He was obviously greater than Abraham (v.4) as well as Aaron, the founder of the Levitical priesthood. Furthermore, he was "without father, without mother, . . . having neither beginning of days, nor end of life; but made like unto the Son of God; abideth a priest continually" (v.3). Such language is hardly appropriate merely because no genealogy is recorded.
If one takes the Bible literally, such statements could be true only of God Himself, appearing briefly in the prein-carnate state of the Second Person, as King of all peace and righteousness. Now this same divine Person, "because He continueth ever, hath an unchangeable priesthood. Wherefore He is able also to save them to the uttermost that come unto God by Him" (Hebrews 7:24-25). HMM