Chaff is the loose, outer covering on wheat and other grains that must be separated in the threshing and winnowing process of harvesting grain. In Bible times, grain was threshed, or trampled, crushed, and beaten, on outdoor threshing floors to separate out the inedible parts of the grain, called chaff. The lightweight chaff would blow away on the wind or sometimes was burned as fuel. In the winnowing process, the grain was then tossed into the air, allowing the wind to further separate any remaining bits of the husk from the wheat. These bits, called chaff, would be carried away in fine particles like dust. In a few instances in Scripture, chaff also refers to dried grass or hay (Isaiah 5:24; 33:11).
Threshing and winnowing by hand were common in ancient times, allowing for vivid biblical imagery. Separating the worthless chaff from the valuable grain was a ready symbol for separating good from evil or showing the difference between God’s treatment of the godly versus the wicked. In Psalm 1:1–4, the people of God are blessed and firmly established, but “not so the wicked! They are like chaff that the wind blows away” (verse 4).
In Isaiah 33, the righteous people of God survive judgment while the wicked nations are consumed. Speaking of the Assyrians, Isaiah says, “You conceive chaff, you give birth to straw; your breath is a fire that consumes you” (verse 11).
According to Hosea, God’s way of dealing with wickedness in Israel was to remove the idolaters like chaff swirling away on the wind: “Therefore they will be like the morning mist, like the early dew that disappears, like chaff swirling from a threshing floor, like smoke escaping through a window” (Hosea 13:3). The powerlessness of wicked people and nations against the judgment of God is compared to chaff floating on the wind: “Although the peoples roar like the roar of surging waters, when he rebukes them they flee far away, driven before the wind like chaff on the hills, like tumbleweed before a gale” (Isaiah 17:13; see also Zephaniah 2:2).
In Nebuchadnezzar’s dream, the ungodly nations of the world, represented as a statue constructed of various elements, disintegrate and disperse like chaff before the victorious kingdom of God: “Then the iron, the clay, the bronze, the silver and the gold were all broken to pieces and became like chaff on a threshing floor in the summer. The wind swept them away without leaving a trace. But the rock that struck the statue became a huge mountain and filled the whole earth” (Daniel 2:35).
In the New Testament, the Messiah, Jesus Christ, is portrayed by John the Baptist as the winnower or harvester of grain: “I baptize you with water for repentance. But after me comes one who is more powerful than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire. His winnowing fork is in his hand, and he will clear his threshing floor, gathering his wheat into the barn and burning up the chaff with unquenchable fire” (Matthew 3:11–12; see also Luke 3:17). Jesus came the first time to save, but the second time He will come to judge the world with righteousness. The chaff—the wicked, the ungodly, the faithless, the unbelieving, the unfruitful—He will separate from the godly and consign to a horrible fate. Therefore, “be always on the watch, and pray that you may be able to escape all that is about to happen, and that you may be able to stand before the Son of Man” (Luke 21:36).