Expositor's Bible Commentary Commentary Luke 3:17

"whose fan is in his hand, thoroughly to cleanse his threshing-floor, and to gather the wheat into his garner; but the chaff he will burn up with unquenchable fire." — Luke 3:17 (ASV)

The question naturally arose whether such a radical prophet as John might be the Messiah (cf. Jn 1:19-25). John responds in several ways. The Messiah is “more powerful” than he is (v.16). The Messiah is worthy of such reverence that even the task of tying his sandals is more than John feels worthy of (cf. Jn 3:30). The Messiah will baptize, not with water in a preparatory way, as John was doing, but actually “with the Holy Spirit and with fire” (v.16). That is, the coming of the Spirit is to have the effect of fire. John uses an agricultural image to explain this. When grain is tossed in the air with a “winnowing fork,” the lighter and heavier elements are separated, with the heavier grain falling on the “threshing floor” and being stored for use. The “chaff,” on the other hand, is burned up. Fire is an ancient symbol of judgment, refinement, and purification (cf. Genesis 19:26; Amos 7:4; Malachi 3:2). John is thus portraying the Holy Spirit as being active in saving, purifying, and judging. The Spirit had definitely, though not frequently, been associated with the Messiah (Isaiah 11:1–2), whose coming would mean also the availability of the Spirit’s ministry.