6 Then one of the seraphim flew to me with a burning coal in his hand, which he had taken from the altar with tongs. 7 He touched my mouth with it and said, “Behold, this has touched your lips ; and your iniquity is taken away and your sin is forgiven.”
The previous verses display the irony – the future spokesman of God had unclean lips and his mouth was unworthy to declare the Lord’s message.
Isaiah recognized the problem and confessed it. God’s response was to send someone to cleanse him from impurity.
God dispatches one of the guardians of the heavenly throne, a seraph, with a hot coal from the altar. Although “seraph” means ‘fiery or burning one,’ this burning coal was too hot for even that guardian to touch directly. He had to use tongs.
Fire burns away impurities in metals. The craftsman who refines silver in a crucible knows when the impurities are gone when he can see his reflection in the molten metal. So also, God allows us to suffer in the fire of trials and the struggles of life to purify us until we can see the reflection of Christ in our own lives.
This coal was taken from the altar upon which Jesus Christ poured His blood. Hebrews 9 describes how Jesus, as our High Priest, entered the Most Holy Place of the Heavenly Temple and poured out His own blood on this altar to pay the price for our sins. We are cleansed by the blood of Christ, the same blood which cleansed Isaiah.
Isaiah looked forward to the time of Christ’s coming. God gave him the privilege to predict the coming of the Messiah and His mission to suffer in our place. Isaiah 53:4-6 states: “Surely he has borne our griefs and carried our sorrows; yet we esteemed him stricken, smitten by God, and afflicted. But he was pierced for our transgressions; he was crushed for our iniquities; upon him was the chastisement that brought us peace, and with his wounds we are healed. All we like sheep have gone astray; we have turned—every one—to his own way; and the Lord has laid on him the iniquity of us all.”
Just as God sent a messenger to cleanse Isaiah, God sent His Son Jesus as the messenger to cleanse all.
So when the seraph touched Isaiah’s lips with the coal, Isaiah’s sin/iniquity was removed. In the same way, when we turn to God, He will forgive us and cleanse us. Sometimes called “The Christian’s Bar of Soap”, 1 John 1:9 states: “If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.”
God prepared Isaiah to be His prophet by cleansing his lips. We also need to be rid of sin to speak God’s word to others.
For personal reflection: Consider the moral failures you listed last week. Do you need to add more? Problem areas include actions we know are wrong, or not doing things we know we should. What about attitudes? We somtimes don’t think of our thoughts as sinful, but hate, jealousy, bitterness, desire for revenge, and lust are iniquities as much as lying, cheating, theft, assault, etc. Now, take those things to God and ask for His forgiveness and cleansing.
Lines from Lynn 
For in the forgiving is the real living, budge yourself to surrender your grudge.
“For it’s in the (for)giving that we receive.’ h/t St. Francis