God has given Isaiah a vision of His throne room. When Isaiah sees the awesome God, he realizes that he is only a sinful man and feels that he is doomed because he has seen the Holy God. Isaiah 6: 5 Then I said, “It’s all over! I am doomed, for I am a sinful man. I have filthy lips, and I live among a people with filthy lips. Yet I have seen the King, the Lord of Heaven’s Armies.” 6 Then one of the seraphim flew to me with a burning coal he had taken from the altar with a pair of tongs. 7 He touched my lips with it and said, “See, this coal has touched your lips. Now your guilt is removed, and your sins are forgiven.” 
The seraph didn’t throw sinful Isaiah out of the throne room, instead he touched Isaiah’s lips with a coal from the altar. The altar of the earthly temple was based on a heavenly model and Isaiah would have seen sacrifices for sin made on the altar. A coal would have been what was left after the finished sacrifice. I think this coal speaks of the finished sacrifice of Jesus who took the sin of the world upon Himself on the cross. Even though Jesus had not yet come to the earth, God is outside of time. It would be Jesus’ sacrifice that would also forgive the sins of those who lived on earth before He did.
I can only imagine the relief Isaiah felt when that burning coal touched his lips and he heard the words “your sins are forgiven.” A great burden had been lifted from him. Our sins, too, can weigh us down. Nothing can be more freeing that being forgiven. We can be thankful that forgiveness is possible because Jesus came and died for our sins upon the cross.
When you feel burdened by your sin forgiveness is only a prayer away. These are four verses that I have found helpful in regard to forgiveness.
- Psalm 86:5 – O Lord, you are so good, so ready to forgive, so full of unfailing love for all who ask for your help. 
- Proverbs 28:13 –People who conceal their sins will not prosper, but if they confess and turn from them, they will receive mercy. 
- 2 Cor. 5:18 – And all of this is a gift from God, who brought us back to himself through Christ. And God has given us this task of reconciling people to him.
- Col. 1:21-22 – This includes you who were once far away from God. You were his enemies, separated from him by your evil thoughts and actions. 22 Yet now he has reconciled you to himself through the death of Christ in his physical body. As a result, he has brought you into his own presence, and you are holy and blameless as you stand before him without a single fault. 
To hear more of the story of Isaiah, listen here: https://podpoint.com/light-of-christ-church-podcast/the-call-isaiah
[1-5] Tyndale House Publishers. (2015). Holy Bible: New Living Translation . Carol Stream, IL: Tyndale House Publishers.