Quite a lot of our confessional documents give space to this topic, with entries in the Augsburg Confession on original sin, justification, the causes of sin, confession, repentance, etc. Because this matter was of central importance to the reformers in their debates with leaders in the Roman Catholic Church of that time, it is no surprise it is given considerable space. It's a complex theological construct, with many moving pieces. Here's one brief articulation, the AC article on justification:
Also they teach that humans cannot be justified before God by their own strength, merits, or works, but are freely justified for Christ's sake, through faith, when they believe that they are received into favor, and that their sins are forgiven for Christ's sake, who, by His death, has made satisfaction for our sins. This faith God imputes for righteousness in God's sight. Rom. 3 and 4.Justification in particular was hotly contested, so Melanchthon, in the longer apology to the Augsburg Confession, wrote his longest and most theological rich (and dense) piece specifically on justification.
Here's where things get tricky, and Lutherans part ways. It seems to be the case that "confessional" Lutherans focus on personal sin and sinfulness and the doctrines surrounding justification itself. "Progressive" Lutherans, among whom I count myself (although I tend to lean in the confessional direction more than some of my colleagues), find the doctrine of justification and forgiveness of sins important but see it leaning towards issues of social and institutional sin, and less towards personal morality.
These are big generalizations, but I think they are accurate.
The result: Confessional Lutherans are critical of progressive Lutherans because they perceive us as being lax (or conforming to societal norms) on topics of personal morality (sexuality in particular). Progressive Lutherans are critical of confessional Lutherans for their failures to address sin at the structural level (sexuality in particular).
Where we really divide is in our approaches bringing our understanding of sin, repentance, and faith to bear on contemporary life. To be really straightforward--many confessional Lutherans think progressive Lutherans don't really believe in sin because we won't call same-sex attraction sin, and many progressive Lutherans don't think confessional Lutherans believe in sin because they won't see their own judgment of the LGBTQ community as complicity in structural, social sin.
Sometimes I wish we would all attempt to understand our theological commitments more carefully in the proposed language of those on the other side of the line. I have trouble, for example, understanding why confessional Lutherans resist liberation theology so strongly. They seem to react strongly to any theology that takes account of personal experience of oppression as a resource for reflection on complicity to sin, and the call for repentance.
Similarly, I have trouble understanding why progressive Lutherans resist forming adequate phenomenological accounts of repentance and forgiveness along the lines of the confessions, including the direct address of personal sin.
One of the oddest developments on the confessional side of the equation is the libertarian tendency in Lutheran confessionalism. I admit, I simply can't completely get my head around this one. Basically, Lutheran libertarians believe social structures (in particular government) should get out of the way to make space for the free proclamation of repentance for the forgiveness of sins in Christ. In other words, if institutions get out of the way, individuals who need to hear the law and be convicted will do such preaching better with complete liberty. Somehow they are inherently more good and able to make this happen than the institutions that constrict such preaching. This is, we might say, a contradiction in terms.
But similarly, social justice advocates, liberation theologians of all sorts, have developed an odd tick of not talking about sin while talking about it all the time. They call it by every other name--racism, homophobia, cisnormativity, xenophobia, misogyny, oppression--but not the name that would make sense to confessional Lutherans, or frankly, a large majority of Christians worldwide. I do not know if this is because they want to avoid speaking of personal sin, or if they feel the word has been so co-opted as to be unusable. Nevertheless, there it is. Our language fails us at the Horizontverschmelzung.
An additional matter has to do with the this world/eternal life dichotomy. Progressive Lutherans tend to see the doctrine of sin and justification mattering for this life. Liberation theology calls for change now, an in-breaking of God's kingdom today. They believe the Marxian critique of religion is valid, that it sometimes functions as an opiate, as in Marx's contribution to the Critique of Hegel's Philosophy of Right:
The criticism of religion is, therefore, in embryo, the criticism of that vale of tears of which religion is the halo... It is, therefore, the task of history, once the other-world of truth has vanished, to establish the truth of this world. It is the immediate task of philosophy, which is in the service of history, to unmask self-estrangement in its unholy forms once the holy form of human self-estrangement has been unmasked. Thus, the criticism of Heaven turns into the criticism of Earth, the criticism of religion into the criticism of law, and the criticism of theology into the criticism of politics.
The theologians have only interpreted the world in various ways; the point, however, is to change it.The Augsburg Confession includes an intriguing article on civil affairs worth quoting in full:
Of Civil Affairs they (Lutherans) teach that lawful civil ordinances are good works of God, and that it is right for Christians to bear civil office, to sit as judges, to judge matters by the Imperial and other existing laws, to award just punishments, to engage in just wars, to serve as soldiers, to make legal contracts, to hold property, to make oath when required by the magistrates, to marry a wife, to be given in marriage.Quite a lot of our current debates about civil affairs hinges on a few lines in this article, especially "save only when commanded to sin," and "lawful" civil ordinances. The Lutheran doctrine of vocation and orders of creation is on full display here, but those little terms are the arena in which the complications of sin and its effects, social justice and its merits, play themselves out.
They condemn the Anabaptists who forbid these civil offices to Christians.
They condemn also those who do not place evangelical perfection in the fear of God and in faith, but in forsaking civil offices, for the Gospel teaches an eternal righteousness of the heart. Meanwhile, it does not destroy the State or the family, but very much requires that they be preserved as ordinances of God, and that charity be practiced in such ordinances. Therefore, Christians are necessarily bound to obey their own magistrates and laws save only when commanded to sin; for then they ought to obey God rather than men. Acts 5:29.
On the flip side, confessional Lutherans point out that progressive Lutherans seem almost exclusively concerned with this world, with little or no conversation about life after this life. Interestingly, the Augsburg Confession doesn't have a particular entry on eternal life per se, but only on Christ's return to judgment. This article follows a fairly traditional separationist line, with Christ separating the godly from the ungodly, each receiving their predictable deserts. But the article is followed by one on free will, and indicates in traditional Lutheran fashion that basically, we don't have free will. So if we are "godly" and righteous, it is only by God's grace and favor and gift. We are made righteous. We do not make ourselves righteous.
This being the case, with God being all in all when it comes to the life after this life, it is fairly clear that there need not be a disjunction, but rather continuity. We can live now in anticipation of what is promised in the right-making God is accomplishing both in this world and for the next.
One last thing. A remarkable aspect of our disagreements concerns the extent to which sin itself corrupts our perception of sin. In other words, sometimes what we call or label sin is itself clouded by our sinfulness. Sometimes we learn it was our sin that labeled something else sin. Nowhere is this more true than in Jesus Christ himself (2 Corinthians 5:21), who became sin who knew no sin. Concomitantly, those who once were sin find themselves surprised by their righteousness.
In this life, those are all rolled up together. In the next, they are sorted and righted by God. In the meantime, God's justifying action is, in my estimation, best understood as social and singular, each and all. The best confessional theology is also liberation theology. And vice versa.