I am struck by the phrase, "He will be like a refiner's fire." My relatives on my father's side were all steel mill workers and so I know something about the heat required to refine and temper steel to make it usable.
When John the Baptist said that the coming Messiah would be like a refiner's fire, he knew first-hand what he was talking about. He had been refined by fire. He took vows of poverty, chastity and temperance from the time he was very young. The kingdom of heaven that will one day come in all of its fullness was experienced as a first fruit in the life and ministry of John. He knew that he had been called to prepare the way for the coming of Jesus and he allowed himself be shaped for his mission.
I remember a young man in one of my congregations who felt called to be a parish pastor. He was a professional man and he had grown up a city boy. His first call, however, was to a small rural parish. He barely knew the difference between a horse and a cow. "Put your books aside for a spell," I counseled him, "and get prepared for another kind of education. Make it a point to make five calls a week."
His first call came during calving. There was little chit-chat. They gave him overalls, rubber boots and invited him to help pull. The telephone began ringing, "Our new pastor helped pull the calf." It was part of the refining process.
Malachi 3:1-4 (NRSV)
1 See, I am sending my messenger to prepare the way before me, and the Lord whom you seek will suddenly come to his temple. The messenger of the covenant in whom you delight--indeed, he is coming, says the Lord of hosts.
2 But who can endure the day of his coming, and who can stand when he appears? For he is like a refiner's fire and like fullers' soap;
3 he will sit as a refiner and purifier of silver, and he will purify the descendants of Levi and refine them like gold and silver, until they present offerings to the Lord in righteousness.
4 Then the offering of Judah and Jerusalem will be pleasing to the Lord as in the days of old and as in former years.