Sermon Video: The threefold office of the Messiah: Priest - Psalm 110:4

The second of the threefold offices of the Messiah (Prophet, Priest, and King), prophet, is expounded by King David himself in Psalm 110 where he writes that God's Messiah will combine his kingly duties with that of the priesthood.  At first this makes no sense, the Law of Moses requires that only those descended from Aaron and the tribe of Levi can be priest and serve at the Temple, so what gives?  David answers the question by explaining that this future priest will be, "in the order of Melchizedek."  The name Melchizedek harkens back to a priest of the LORD who served in what would become Jerusalem during Abraham's lifetime.  He is brought into Abraham's story in Genesis only briefly, but the precedent is understood by David as an exception to the rule of the Law (since it preceded it).  The book of Hebrews expounds upon this topic (chapters 5-7), but we ought to be able to reason out that the God who wrote the Law is capable of setting it aside (abrogating, expanding, modifying, take your pick) to fulfill his purpose.  His purpose in this case?  That Jesus Christ might not only be the priest who makes the once-for-all offering to bring salvation, but the Lamb of God being sacrificed as well.