Martin Luther was not the type of person who'd say, "On the one hand, this . . . on the other hand, that. Let me just clarify what I said so nobody will take offense." If he had been, we might not have had a Reformation.
He often used hyperbole that made his opponents demonize him and sent his proponents scrambling to demonstrate from his other writings what he really meant. But his words never got lost in the white noise.
This is what he said: "God does not save those who are only imaginary sinners. Be a sinner, and let your sins be strong (sin boldly), but let your trust in Christ be stronger, and rejoice in Christ who is the victor over sin, death, and the world."
What on earth could he have meant by that? Is he saying, like many Christians believe today, that the Cross covers continued, willful sin that we refuse to surrender? No, he is not. How do I know this? By interpreting those words in the context of his whole theology. He said elsewhere: "If you do not give forth such proofs of faith [good works], it is certain that your faith is not right. Not that good works are commanded us by this Word; for where faith in the heart is right, there is no need of much commanding good works to be done; they follow of themselves. But the works of love are only an evidence of the existence of faith." (Italics added.) Although Luther stressed that we are saved by faith alone, faith by its very nature produces good works. The idea that a person can be saved while continuing on exactly like before is a dangerous misunderstanding of both the Apostle Paul and Luther.
So what, then, did he mean? He is talking about the power of the Cross to forgive and heal all sin. Real sin, not just the imaginary kind where deep down we feel that we were justified.
Then there are times when I decide to start praying more and becoming less lukewarm, and it never fails--I always end up falling flat on my face shortly afterwards. It must be because Satan suddenly considers me worthy of his attention and brings to the surface something that had been in my heart all along. When I'm still down, he says: "Look at you. What a disgrace! And you call yourself a Christian!"
It is at that moment that Luther's words become relevant. There are many ways I can react. I can justify myself and add that one to my collection of "imaginary" sins (although at this point I'm starting to think that maybe all my sins are real), I can try harder next time, I can despair, or I can hide from God like Adam and Eve did after the Fall. In other words, I can let Satan put me on the defensive.
Or I can act like the Cross actually means something. Like it is enough for sinners like myself. I can say to Satan: "Yes, I AM a sinner! Thank you for the reminder, because sometimes I fool myself. But the Cross is sufficient for ALL sins of ALL people, both to remove the guilt and the stain." Or, in the words of Luther, I can say: "Indeed, by calling me a sinner you are supplying me with weapons against yourself so that I can slay and destroy you with your own sword; for Christ died for sinners." God's grace is sufficient for me, and his grace gives me not just forgiveness but victory over sin as well.
In Luke 7, Jesus demonstrates to a Pharisee how he welcomes even the worst of repentant sinners, and the power of his forgiveness. A woman had brought an alabaster jar of expensive perfume, and she kept anointing his feet with the perfume, weeping, and wiping his feet with her hair. The Pharisee, who hosted the party, was indignant that Jesus didn't seem to know what type of woman she was--a sinner. But Jesus explained, "Do you see this woman? I entered your house; you gave Me no water for My feet, but she has wet My feet with her tears and wiped them with her hair. You gave me no kiss; but she, since the time I came in, has not ceased to kiss My feet. You did not anoint My head with oil, but she has anointed My feet with perfume. For that reason I say to you, her sins, which are many, have been forgiven, for she loved much; but he who is forgiven little loves little."
She was a bold sinner, but her trust in (and love for) Christ was stronger than her sin, so she experienced his victory over sin, death, and the world. The power of the Cross was enough for her, and it is enough for us.