Isaiah needed a cleansing and a covering of his sin. The living coal from off the Altar of Burnt Offering, symbolizing the fire of the Wrath of God and the Blood of the Lamb of God, when brought in contact with his “unclean lips,” removed his iniquity and expiated his sin. THE ALTAR The “Altar” represented Calvary, to which sinful man must be exposed before he can be cleansed and saved. We are actually seeing in this experience what takes place in the spiritual upon the conversion of a lost sinner.