God appointed Christ as king-priest when He sat down at the right hand of God following His ascension ( Hebrews 1:5). The title "Christ" (Anointed One) stresses our Lord"s humility. As the Anointed of God, Jesus (cf. Hebrews 4:14) did not exalt Himself as He might well have done. [1] These two offices and functions were primary in the writer"s argument in this epistle. Psalm 2:7-9 and Psalm 110:1 (cf. Hebrews 1:13) predicted Messiah"s reign. Psalm 110:4 also predicted His priesthood. The same God who appointed Jesus as His Son also appointed Him high priest forever (cf. Hebrews 6:20; Hebrews 7:17; Hebrews 7:21; Hebrews 7:24; Hebrews 7:28). We have a great high priest, Jesus the Son of God, and it is as He is Son that He carries out His vocation of high priest. [2] No other New Testament writer referred to Psalm 110:4, but this writer quoted it three times (cf. Hebrews 7:17; Hebrews 7:21) and alluded to it eight more times (in chs5-7). [3][source]
"The appeal to Melchizedek, who as the first priest mentioned in Scripture is the archetype of all priesthood, validates Jesus" priesthood as different from and superior to the Levitical priesthood." [4][source]
"When ... Jerusalem fell into David"s hands and became his capital city ( 2 Samuel 5:6 ff.), he and his heirs became successors to Melchizedek"s kingship, and probably also (in a titular capacity at least) to the priesthood of God Most High." [5][source]
"All that a priest does in offering sacrifice for men Christ does. But whereas they do it only symbolically, he really effects atonement. [source][source][source]
"There was no succession of priests from Melchizedek and thus no "order." Jesus, however, was a priest of this kind-not like Aaron and his successors." [6][source]