So Isaiah is describing a vision he had, where he was located in the presence of the Lord. This is not the Lord visiting him where he resides, but him visiting the Lord where He reigns. He was transported, not physically, but experientially, in a comprehensively sensory way, into the throne room of the pre-incarnate Jesus. That's mind boggling!
And I'll just admit it's hard for me to get there in my own head. I don't know how to imagine that even. But the description Isaiah gives us is helpful in terms of impact...
Notice the description is not of Jesus' face, but of the train of his robe and the surroundings. Either Isaiah can't even look upon the face of Jesus, or he had no words to describe it... he is just overwhelmed by the breathtaking scene, the glory and awe and wonder of the moment, and he is driven instinctively and instantly to his knees and face. Being in the presence of Christ, surrounded by the glory of God, makes him immediately and intensely aware of his own unworthiness, guilt, weakness, need and even vulnerability.
The scene he presents of being in the presence of Jesus, is one of angels worshipping, him seeing himself and humanity as unclean, leading him to repentance and worship, and then being forgiven, welcomed and then sent by Jesus to proclaim his glory and grace to Israel. This is the gospel at work 700 years before Jesus entered human history. Isaiah is experiencing very personally and viscerally the same thing all Christians would come to experience in salvation through Jesus.
Coming alive to God means that we encounter the living Jesus, who gathers us to a worshipping community, drives us to our knees in repentance, forgives us of all our guilt, welcomes us into his loving presence and new family, and then commissions us for ministry to proclaim this good news of His grace and glory to others, many of whom will not hear him but some of whom he will save and bring to himself.
There's a ton in this text... much more than this, but the gospel explodes out of this scene to me in a really powerful way. And it inspires worship and gratitude and awe in me. What a great salvation and glorious gospel and beautiful King we have received!