The cross prepares the new creation in which God, in the person of the Holy Spirit, can take up residence. The goal of the forgiveness of sins is God’s perpetual indwelling. Jesus’s blood provides an internal cleansing specifically to prepare a place for the indwelling of the Holy Spirit. This is what the story of Noah is all about. The earth before the flood, like the hearts of every person, is evil and unclean. God then sends judgment in the form of cleansing, just like his sending Jesus to the cross. This cleansing results in a new creation that is innocent from sin-guilt, thereby creating a holy place for God to reside. The dove is the Holy Spirit that takes up residence in the newly created heart of the believer.
The application of this can be summed up in John’s words, “I must decrease, and he must increase” (John 3:30). Jesus is the main character on the stage of the story of redemption in the world, not us. We must be careful not to be tripped up the temptation to think that God’s saving work through us is any work of our own. It is all His work. Jesus is the one who takes away the sin of the world, not us.