Prior to his conversion, Martin Luther wrestled with the reality of sin in his life. Luther devoted himself to the Roman Catholic system of good works in order to appease his sinful conscience, but none of those works ever satisfied his guilty conscience. Only when he discovered Paul’s teaching of justification by faith, did he discover “the gate of heaven” and receive the grace of God that is found in Jesus Christ. He would devote the rest of his life to proclaiming this good news that justification is to be received by faith alone.
But Luther’s message was not limited simply to preaching about God’s free grace in Christ. Luther understood that before justification by faith made sense, one also had to embrace Scripture’s teaching regarding sin. While Luther experienced deep conviction of his own sin, he knew that not everyone shared his experience or sensitive conscience. Therefore, the acknowledgment of sin could not ultimately be rooted in subjective experience. Rather, like justification, our sinfulness also has to be received by faith based on God’s Word.
Even if we do not recognize any sin in ourselves, we must nevertheless believe that we are sinners. Hence the apostle says: “I am not aware of anything against myself, but I am not thereby justified” (1 Cor. 4:4). For just as the righteousness of God is alive in me by faith, so by the same faith sin is alive in me; i.e., by faith alone we must believe that we are sinners, because it is not obvious to us. If truth be told, most of the time we do not seem to be conscious of ourselves [as sinners]. Therefore we must stand by God’s judgment and believe the words by which he tells us that we are unjust, because he cannot tell a falsehood.
In an age that places such an emphasis on subjective experience, here is a reminder that our ultimate trust must rest in God’s Word rather than ourselves, even when it comes to our sinfulness. And this makes a big difference.
For those struggling with sin
If you’re someone who feels the weight of your sin, realize that your experience is not the final work about your sin, but only the starting point. Allow that experience of sin to humble you so that you’re willing to hear what God has to say to you about your sin. In one sense, you don’t need to be shocked and surprised by your sin, because if you are a Christian, you already confessed that you are a sinner. Romans 1-3 is a description of your problem, not merely the problem of those “out there.” Your experience of sin is simply confirmation of how deep the problem goes and how desperately you need a Savior. Rather than being overwhelmed by certain sins, we confess by faith that our entire condition is fallen and our only hope is Christ.
For those tempted by self-righteousness
But what if you’re someone who doesn’t feel great emotional sorrow over your sin? As Luther said, what if you’re someone for whom their sin “is not obvious”? In the same way, you also need to hear what God says to you about your sin, and you need to believe it. Even though your life may seem all put together, God’s Word speaks to us about the deeper reality of our sin. Even while you do good works and live disciplined lives, Scripture warns us that our righteous deeds apart from Christ are like filthy rags (Is. 64:6) and that our hearts are deceitful above all things and beyond cure (Jer. 17:9). This is not to say that you should wallow in sin and guilt. But by faith, all must confess that Scripture rightly reveals our fallen condition apart from Christ and that our self-righteousness only condemns us. It is only as we accept this truth by faith that we will then be ready to receive the gospel as a gracious gift, rather than as a vindication of our morality.
For the preacher
Therefore, pastor, preach about sin! Faith comes by hearing the Word of God. This is true not only for understanding justification, but also for understanding our sin. So don’t be afraid to preach about sin, even if you’ve got a congregation full of seemingly morally upstanding people, or hurting people, or people with all kinds of other pressing concerns. It is so much easier to talk merely about our brokenness or injustices or the fallen world that we live in, and these are important topics. But in order for the gospel to make sense, we must also preach about our personal sin. Teach them what Scripture reveals and call them to believe it, to confess their sin by faith. Because only then, will they be ready to rejoice at the wonder of the gospel.
 Luther’s Works, 25:215.