Much has been said and written about sin over two thousand years of Christian history. The same is true of the struggle against it. And even before Christ came into the world, people spoke about this too.
Yet both in the past and today, sin is often spoken of as the violation of a moral norm. Or as a source of evil for one's neighbor. The author of the epistle, meanwhile, draws attention to something else: he speaks of an evil and faithless heart that separates a person from God. He says something that, on the one hand, appears self-evident, and on the other hand returns us to that understanding of sin which could be called originally biblical.
The biblical books were by no means written by philosopher-moralists. And the authors of the biblical books considered sin evil not because sinful acts contradict certain moral norms, even if those norms were established by God. After all, God too is not a moralist. He hates sin not because it is beautiful and worthy for a person to be moral, or at least not only for that reason. Of course, sin distorts the image of God in a person, and this cannot gladden God. But the most terrible thing lies elsewhere: sin separates a person from God. And the most terrible thing here is that God can do nothing about it.
The human person is free, and God respects that freedom. And if this free person, abusing his freedom, builds between himself and God a wall made of his own sins and their consequences, God has nothing left to do but wait for repentance and a new turning. This wall is the most terrible thing sin can bring to a person. And not because everything else is unimportant. It is simply that God can fully deal with everything else, if only the person allows Him to do so. But only the person himself is able to break through and tear down the wall.
Yet this requires firm resolve, which is impossible for a person whose heart is pierced through by sin or who lacks faithfulness. For conversion is above all a change in the spiritual direction of the heart, in what modern psychologists call its intention. And this new intention must be deep and stable enough; otherwise the wall of sin cannot be pierced or broken down. And then new conversion and spiritual renewal will have to be forgotten. If not forever, then for a long time.