Letter format might not seem like the most interesting thing to talk about. In fact, in many ways, the format of Paul's letters is something that we breeze by. I think this happens for two main reasons: 1) we don't think to consider how the format itself might be significant to our understanding and 2) it is formatted in a way that is not wholly unlike modern letters. It has the to and the from and a general greeting. Bunch of common letter stuff. And yet, I think that picking up on Paul's letter format, and thus how Paul organizes the presentation of ideas, can really aid us in understanding the letter as a whole. In fact, there are a lot of ways in which learning about Paul's letter format can guide our understanding. One of those ways is with respect to counseling fellow Christians struggling with sin.
A Grace and Peace Inclusio
An inclusio is a literary device whereby a writer brackets a section of content with two identical or similar phrases or concepts; one at the beginning and one at the end. This is a device well-known to readers of the Psalms. Perhaps my favorite example is with Psalm 73 where the phrase "but as for me" and the comment of God as being good bookends the entire psalm. But this device is not limited strictly to poetry, I would argue it finds itself in much of the Pauline corpus as well.
In order to see this we must first consider what Paul's letter format even is. By-in-large, Paul's letters follow this format:
Opening: X to Y, grace and peace
Thanksgiving
Body: doctrine followed by hortatory
Closing: peace benediction, greetings, grace benediction
This format largely resembles the typical hellenistic letter format of Paul's day. He doesn't follow this exactly with each letter and yet, by-in-large, we can trace this structure within his corpus.
What you may already see as you consider this format is that the opening and the closing share string similarities; the presence of grace and peace. These elements are present at the beginning of Paul's letters as well as the end. In fact, amongst the various elements of Paul's letter format, this grace and peace inclusio is the most stable throughout Paul's corpus. In fact, even those letters which break the norm the most still contain this element.
Consider Galatians. The opening of Paul's letter to the Galatians is a quite a unique letter compared to the others. The 'X to Y' element within the opening breaks the norm by containing a firm reminder of Paul's apostolic authority. It also is completely void of a thanksgiving section which is replaced by statement of pure shock toward the Galatians’ distortion of the Gospel. Continuing into the body section, Paul still does not mince words and wonders if they are perhaps bewitched (Gal 3:1). Twice in this chapter he calls them foolish! Considering these facts, we would by all means expect Paul to remove his grace and peace inclusio... and yet it remains. It is more likely than not that Paul's intention behind this literary move (which persists even in Galatians!) is that he aimed for his writings to be viewed within the all-encompassing framework of divine grace from beginning to end.
Practicing the Grace and Peace Inclusio
There is something strange and wonderful that happened when a person is born again. There is a transferring of dominion from that of sin to that of the kingdom of the beloved Son (Col 1:13, also see Rom 6:18 and 1 Cor 6:9-11). With this transfer comes a new way of life; a kingdom ethic (1 John 1:5-10). And yet, we are foolish to think that the grace that adopted us into this fellowship with God will then abandon us to venture life on our own. It is grace from beginning to end (Phil 1:6). Thus, the theological structure of a grace and peace inclusio permeates the message of the Bible.
And yet, just as Paul anticipated would be the thinking of the Roman Christians in Rom 6, we can improperly view this as a license to sin. That is by no means the case and should not at all be the framework of our counseling fellow Christians. Paul viewed sin as death and so should we (Rom 6:23). But he also viewed sanctification as a lifelong and grace-fueled process and so should we (2 Cor 7:1, Phil 2:13). And thus, we should bookend our counseling fellow Christians in this same light. Push people to do the hard work of true repentance and putting on holiness (Eph 4:22-24). But season your counsel with grace from beginning to end.