Then I said, “Woe is me for, for I am ruined! Because I am a man of unclean lips, and I live among a people of unclean lips. For my eyes have seen the LORD of hosts.”
Then one of the seraphim flew to me with a burning coal in his hand, which he had taken from the altar with tongs. He touched my mouth and said, “Behold, this has touched your lips; and your iniquity is taken away and your sin is forgiven.” Isaiah 6:5-7
Isaiah echoed Moses when Moses resisted God’s call to lead Israel out of captivity, saying he was unworthy in speech, literally, uncircumcised, i.e., unclean, lips. Moses’ resistance was not out of concern for his speech ability. To the contrary, Stephen says Moses was a man of power in words and deeds. Rather, Moses was convicted of his unworthiness, his sinfulness, his “uncircumcised lips.”
Isaiah’s declaration foreshadows Peter’s exclamation upon encountering Jesus’ words and power: “Go away from me Lord, for I am a sinful man.”
Isaiah’s statement is about the mouth, and the remedy is to touch his lips.
The lips? Not the heart, the mind, the eyes, the hands, the feet? Why the lips? Why the mouth?
James wrote, “2 For we all stumble in many ways. If anyone does not stumble in what he says, he is a perfect man, able to bridle the whole body as well. 3 Now if we put the bits into the horses’ mouths so that they will obey us, we direct their entire body as well. 4 Look at the ships also, though they are so great and are driven by strong winds, are still directed by a very small rudder wherever the inclination of the pilot desires. 5 So also the tongue is a small part of the body, and yet it boasts of great things.” James 3:2-5.
And Jesus explained, “’Do you not understand that whatever goes into a person from outside cannot defile the person, 19 because it does not go into the person’s heart, but into the stomach, and is eliminated?’” (Thus He declared all foods clean.) 20 And He was saying, “That which proceeds out of the person, that is what defiles the person. 21 For from within, out of the heart of a person, proceed the evil thoughts, fornications, thefts, murders, adulteries, 22 deeds of coveting, wickedness, deceit, sensuality, envy, slander, pride and foolishness. 23 All these evil things proceed from within and defile the person.” Mark 7:18b-23.
The mouth is the outflow. What proceeds from there reveals the heart. Unclean lips are not an occasional slip of the tongue. They are the indicator of a deeper heart condition, one that needs God’s purification and forgiveness.
Isaiah had the perception to understand his and his people’s “unclean lips” revealed a sinful heart. Yet this perception and confession was not enough. Cleansing took divine intervention: an altar – a fire on the altar– a seraphim – a burning coal too hot for even the seraphim to touch but required tongs. The initiative and the power to forgive are all God’s.
The immediate result: “8 Then I [Isaiah] heard the voice of the Lord, saying, “Whom shall I send, and who will go for Us?” Then I said, “Here am I. Send me!”
As with Moses, who obeyed God’s call.
As with Peter, who 
dropped his nets and followed Jesus to become a fisher of men.
Isaiah’s “work” from that time forward is, ironically, words. He was a prophet. He spoke words inspired by God. We have no record of Isaiah performing any miracles or fighting any battles. No exploits. Just words. From lips that were formerly unclean, now cleansed by the Burning Coal.
Isaiah writes some of the most beautiful, inspired, powerful and prophetic words ever written. Most of Handel’s Messiah is from Isaiah’s writings, words from formerly unclean lips. For example, wrote (spoke) Isaiah:
Yet those who wait for the Lord
Will gain new strength;
They will mount up with wings like eagles,
They will run and not get tired,
They will walk and not become weary. Isaiah 40:31
And
But He was pierced through for our transgressions,
He was crushed for our iniquities;
The chastening for our well-being fell upon Him,
And by His scourging we are healed.
All of us like sheep have gone astray,
Each of us has turned to his own way;
But the Lord has caused the iniquity of us all
To fall on Him. Isaiah 53:5-6.
“Woe to me,” correct appraisal though it was, became in an instant, “Here I am, send me.”
God made a way. “Your iniquity is taken away.” “Your sin is forgiven.”
We are all unworthy. We are all unqualified. We all have unclean lips that reflect our deeper sinful condition. And yet, God draws us into His presence, touches us, cleanses us and forgives us. And sends us.
Now, let’s get going. There is important work to do.
Here I am LORD. Send me.