"Keep in mind that Scripture says that nothing unclean can enter heaven and that our God is a consuming fire. No attachment to sin can survive in his presence, can it?"
Of course. Our sins are covered by the blood of Christ. Blood is required for the remission of sins. Once and for all it was done on the Cross. That is faith -- trusting that all of our sins are pardoned by God.
Nice exposition of Lutheran theology; too bad it's not Biblical. Why did John the Baptist say, "Behold the Lamb of God, who takes away the sin of the world", not "Behold the Lamb of God, who covers up the sin of the world."?
If your sins are merely covered, not wiped away, you're still going to hell. Luther said that the justified man was a snow-covered dungheap. The Bible says that God is a consuming fire. What happens when a snow-covered dungheap contacts a consuming fire?