Then one of the seraphim flew to me, having in his hand a live coal
which he had taken with the tongs from the altar. And he touched my mouth with
it, and said, “Behold, this has touched your lips; your iniquity is taken away,
and your sin purged.”
The seraphim burned Isaiah’s lips with the coal. The smell of the burning was sweet in the nostrils of God because it was the smell of impurities being burnt out. This was not just an external cleansing, but an internal, profound cleansing that left the prophet spiritually whole. Isaiah was really seeing a preview of the King of Kings’ saving work on the cross. Now, God does not have to clean through a seraph because he does so through His Son, the Savior.