Who Was Melchizedek?
Ps.110:4, says "The Lord hath sworn, and will not repent, Thou art a priest forever after the order of Melchizedek."
The word order in this verse means manner, fashion, cause, sake, intent, reason, estate, end, regard, and succession. 'Thou art a priest forever after the (manner, fashion, style, way, or succession) of Melchizedek. The first time we see Mechizedek in the Scriptures is found in Genesis 14:18-20, which says "And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God. And he blessed him, and said, Blessed be Abram of the most high God, possessor of heaven and earth: And blessed be the most high God, which hath delivered thine enemies into thy hand. And he gave him tithes of all."

1. The first thing we need to understand about Melchizedek is that he was the king of Salem. But not only was he a king, he was a priest also. This is the first time in scripture that we see king and priest joined in one role.

2. The second thing we need to notice is that Melchizedek was NOT an appearance of the pre-incarnate Christ: he lived and reigned in Salem, so he was not a Theophany (that is God appearing in another form). The book of Hebrews plainly compares the two. If Melchizedek was Jesus, then Jesus would be a reincarnation of himself, the first coming of Jesus would really be the second coming of Jesus.

3. The third thing we must also understand is that Melchizedek was NOT Shem. We have read and know Shem's ancestry, when the Bible plainly says Melchizedek's genealogy was not recorded. But why have people throughout the centuries debated about his deity and his genealogy? These debates were based on a misinterpretation of Hebrews chapter 7. The backdrop of Hebrews 7, is a few chapters before in chapter 5:5,6, which says "So also Christ glorified not himself to be made an high priest; but he that said unto him, Thou art my Son, to day have I begotten thee. As he saith also in another place, Thou art a priest forever after the order of Melchisedec." How can Melchizedek's priesthood be eternal or everlasting if he was just a man? So was Melchizedek just a man? Yes! Melchizedek was not eternal or everlasting. Melchizedek died just like the other priest under the Law of Moses, but the only thing with that is, it is not recorded. Which makes his life seem as though he did not die. Under the Law priest had to have their record of genealogy (Ezra 2:59-62). But the Melchizedek Priesthood is not under Law, so the reason why the Melchizedek Priesthood is everlasting is because it is the person who is the priest who is eternal and everlasting which makes the priesthood eternal and everlasting, Jesus Christ; "...THOU ART a priest forever after the order of Melchisedec." So then, the order of Melchizedek is the manner, style or way he operated as priest. The key in understanding Melchizedek is separating what is type from what is literal. [Source/more]
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Who Was Melchizedek?