Martin McNamara, «Melchizedek: Gen 14,17-20 in the Targums, in Rabbinic and Early Christian Literature», Vol. 81 (2000) 1-31
The essay is introduced by some words on the nature of the Aramaic translations of Gen 14 used in the study (the Tgs. Onq., Pal. Tgs. as in Tgs. Neof. I, Frg. Tgs., Ps.-J.). Tg. Neof. identifies the Valley of Shaveh (Gen 14,17) as the Valley of the Gardens (pardesaya). The value of Tg. Neof.s evidence here is doubtful. Most Targums retain Melchizedek as a personal name (not so Tg. Ps.-J.). Salem of v. 18 is identified as Jerusalem. Melchizedek is identified as Shem, son of Noah, mainly because of the life-span assigned to Shem in Gen 11. The question of Melchizedeks priesthood in early rabbinic tradition and in the Targums (Tg. Gen 14; Tg Ps. 110) is considered, as is also the use of Jewish targumic-type tradition on Melchizedek in such early Fathers as Jerome, Ephrem, and Theodore of Mopsuestia.
before the levitical priesthood began with Aaron, were priests. The identification of two named biblical characters is not proper to Shem-Melchizedek. We have other examples in the Targums, particularly in Tg. Ps.-J. Thus Tg. Ps.-J. identifies Putiel of Exod 6,25 with Jethro (inverting the order: "... one of the daughters of Jethro he is Putiel") and Phinehas of Num 25,12 with Elijah (although here implicitly, without mention of Elijahs name).
3. The Demotion of Melchizedeks Priesthood in Rabbinical Sources (Ps 110,4)
It has been noted above that in accepting the identification of Melchizedek with Shem R. Ishmael did not have any polemical point to make. The same cannot be said of his statement which follows immediately on this regarding Melchizedeks priesthood. This, he says, was taken away by God from Shem (=Melchisedek) and given to Abram. Shem (=Melchizedek) was a priest but his descendants were not. God transfers the priesthood of Shem (=Melchizedek) to Abraham and addresses Ps 110,1 to him: "Sit on my right hand...", as he also does Ps 110,4: "Your are a priest for ever according to the order of (ytrbd l() Melchizedek", which is interpreted as meaning "on account of what (wrwbyd l() Melchizedek said". The reason for the demotion of Melchizedeks priesthood is seen in Melchisedek having blessed Abram before he uttered his blessing to God Most High. As Petuchowski observes: there can be no doubt that R. Ishmaels reference to Melchizedek is polemical28. But against whom is R. Ishmaels polemic directed?
One possibility is that his target is the Christian understanding of Melchizedeks priesthood, particularly as presented in the Epistle to the Hebrews (especially Heb 7, with the use of Gen 14,17-20 and Ps 110,4). L. Ginzberg believed that it was very likely directed against the Christians, such as the author of Hebrews 7,1-3 and especially Justin (Dialogue with Trypho, 33 and 96) who took Melchizedek to be a type of Jesus29; likewise R. Travers Herford30, P. Billerbeck31