Melchizedek was king of Salem and a priest of the Most High God.  We are told that Jesus was from the order of Melchizedek (Heb. 7:17; Ps. 110:4).  Please explain.

You can read about the Old Testament account of Melchizedek in Genesis 14:18-20.

The purpose of the book of Hebrews was to persuade Jewish Christians to not fall away from Christianity and return to Judaism.  Thus, the author gives several arguments throughout the book as to why Jesus is superior to various aspects of Old Testament Judaism.  In Hebrews 7, the author uses Melchizedek to prove the superiority of Jesus to the Levitical priesthood.

Under Mosaic law, priests had to be from Levi’s tribe (Heb. 7:5).  Once they died they stopped being priests (Heb. 7:23).  However, Melchizedek was a priest not from Levi’s tribe, having lived well before the Levites came into existence as a tribe.  Plus, we know nothing of his ancestry, birth, or death (Heb. 7:3).  That makes him and his priesthood very different from the Levitical priesthood.

Jesus is very much like Melchizedek (Heb. 7:17; Ps. 110:4; cf. Heb. 7:11-25).  Christ also was not from Levi’s tribe (Heb. 7:14).  While Melchizedek was a priest forever metaphorically due to the absence of any record of his death, Jesus is a priest forever literally.  That’s why He is more like Melchizedek than the Levites, and His priesthood is superior to theirs.

Likewise, the Israelites would pay tithes to the Levitical priests (Heb. 7:5).  However, the ancestor of the Levites, Abraham, paid tithes to the priest Melchizedek (Heb. 7:6-9).  In fact, in one sense even Levi himself paid tithes to Melchizedek through Abraham (Heb. 7:9-10).  This shows Melchizedek’s priesthood is superior to that of the Levites (Heb. 7:7).

Jesus’ priesthood is similar to that of Melchizedek’s (Heb. 7:17; Ps. 110:4) in that they both are superior to the Levitical priesthood because we as Christians likewise give to Jesus, our Priest, who in turn blesses us and thus shows His superiority over us.