Malachi 3:1-4 is one of the readings for the second Sunday of Advent. Christians have interpreted the passage as a prophecy of John the Baptist. But the messenger of verse 1 probably was Malachi or another prophet of the time.
The book of Malachi came into being after the Babylonian Exile, probably shortly after the second Temple was established. So Malachi cares a lot about the priesthood. He condemns the sins of the priesthood in the first chapter. He is not nice about it.
The kind of invective Malachi uses to blast the corrupt establishment tends today to get reserved for political parties throwing mud at each other. So I think we likely think such judgemental assaults represent spin. Malachi, though, isn’t trying win an election. He actually calls for repentance.
He wants a painful return to truth. He is not just trying to stick it to the man or get revenge on political enemies. He envisions real but painful renewal through a “refiner’s fire.” This is not an image of the torments of hell. It is a fire of purification, an image drawn from ancient metallurgy.
But he looks to a day when there will be a worthy priesthood. Last week the Advent reading from Jeremiah spoke of a righteous descendent of David who would be a worthy king. Malachi speaks of a purified priesthood that would offer worthy sacrifices.
One Christian way of speaking about the person of Jesus has seen him as prophet, priest and king. So a Christian, at Advent time, might see this passage from Malachi as pointing to a future righteous priest and see it fulfilled in Christ. The New Testament book of Hebrews bears such a perspective.