The Greek verb diakathorizō means to thoroughly cleanse or purge completely — a thorough, comprehensive cleaning. It appears in Matthew 3:12 and Luke 3:17 in John the Baptist's vivid image of the coming Messiah: 'His winnowing fork is in his hand, and he will thoroughly clear his threshing floor and gather his wheat into the barn, but the chaff he will burn with unquenchable fire.'
John the Baptist's proclamation of the Coming One's diakathorizō — thoroughly cleansing His threshing floor — is one of the most powerful messianic images in the New Testament. The threshing floor represents the whole of humanity; the Messiah comes not merely to adjust or reform but to do a complete, thorough work of separation and purification. The wheat (the redeemed) and the chaff (the perishing) cannot coexist forever. John saw judgment as primary; the Cross reveals that the Messiah first came to do the internal cleansing — purifying hearts through the Spirit (Acts 15:9) before the final external separation. The church's purity also reflects ongoing diakathorizō.