Martin Luther offers these reflections on the account of the adulterous woman in John 8:1-11.
Recognize your sin
[Jesus is saying,] “The kingdom of Christ is not one of condemnation. I am not here to condemn you, but to remit the sins of those who, like you, are where death, the devil, evil consciences, accusers, and judges have come to plague them. The slogan in My kingdom is: I forgive you your sin; for in My kingdom no one is without forgiveness of sins. Therefore you, too, must have forgiveness. My kingdom must not be in disorder. All who enter it and dwell in it must be sinners. But as sinners they cannot live without the forgiveness of sins.”
If I am a sinner, the matter is not ended there; the sins must be forgiven. Thus none but sinners come into this kingdom.
But do not let this prompt you to say: “Well, we will remain in sin.” No, you must learn to feel and recognize your sin.
Feel your sin
These Pharisees did not have to become sinners; they were sinners already, and they became even greater sinners when Christ uncovered their sins with the words: “Let him who is without sin among you be the first to throw a stone at her.”
A sinner is a person who feels his sin. The Pharisees, these rogues, were no sinners; but they became sinners when Christ said: “Let him who is without sin, etc.” Now they became sinners. But they despaired and slunk away. In their arrogance they hid their sin and would not await Christ’s second statement: “Neither do I condemn you.”
Embrace the forgiveness of your sin
Thus only those sinners belong in the kingdom of Christ who recognize their sin, feel it, and then catch hold of the Word of Christ spoken here: “I do not condemn you.”
These people constitute the membership of Christ’s kingdom. He admits no saint. He blows them all away. He expels from the church all who lay claim to holiness.
If sinners enter, they do not remain sinners. He spreads his cloak over their sins and says: “If you have sinned, I remit your sins and cover them.”
To be sure, sin is there. But the Lord in this kingdom closes his eyes to it, covers it, forgives it, and does not impute it to the sinner.
Live in the forgiveness of your sin
So a living saint and member of Christ stands here, made out of an adulteress who had been infested with sin but whose sin is now forgiven and covered.
Even if sinners are knaves and criminals, their sins will be forgiven, as long as they feel them, repent of them, and ask God for forgiveness.
If you have tasted the law and sin, and if you know the ache of sin, then look here, and see how sweet, in comparison, the grace of God is, the grace which is offered to us in the gospel. This is the absolution which the adulteress receives here from the Lord Christ.