Melchizedek is unique among major Biblical characters in that he has no genealogy and no record of his death. Hebrews makes use of this point to show that he, conceptually, is an eternal priest. As such, he serves as a prototype for a priestly order separate from that of Aaron. That Y'shua is a priest according to the order of Melchizedek is established by Psalm 110. Hence, Y'shua is a priest forever.