Consider Genesis 1 - first darkness then light; first the seed then the fruit; first forming then filling.
Consider Genesis 2 - first the man goes into death-sleep then he's raised to unite with his bride.
Consider Genesis 3 - first Adam takes us into curse, then the promised Seed will bring deliverance.
Consider Abraham - first barrenness according to the flesh then life according to the promise.
Consider Moses - even before Israel enters the land he tells them of their inevitable exile and then the LORD will bring them home with an almighty atonement.
Consider Isaiah - he must proclaim the hacking down of Israel's tree until only the Holy Seed is left (Isaiah 6).
Consider Jeremiah - his word to the nation is first judgement then salvation (Jeremiah 1:4-10; cf Jeremiah 31)
Luther did not invent an arbitrary distinction with law and gospel. Rather, he named the pattern of the Word in evidence on every page. This patterns goes through death and, only in going through death, we then enter resurrection. (You'll notice how law-gospel preaching goes hand in hand with a theology of the cross).
Therefore our proclamation should take the same shape. We preach the inability of the flesh, of the will, of human effort when it comes to establishing the wondrously good life of God's kingdom. The law is good - really, fantastically good. But it reveals that we are bad - stinkingly, horrifyingly bad. We preach the reality of our own spiritual death and then we declare the life that comes from outside ourselves. We point to the Lamb of God who takes away the sins of the world. You could call that law-gospel preaching if you like, but Luther has no trademark on it. It's the kind of thing you have to preach if you believe salvation comes only from Christ and never from us.
Anyway... I was teaching these kinds of things recently and two people asked questions in quick succession. The first asked: "What about Leviticus 26-27 - that takes the pattern of blessings then curses." The second asked about Luke 6 - Jesus proclaims blessings then woes. If the shape of the word is law then gospel, why are these significant portions of Scripture proclaiming a 'positive message' and then a 'negative message'?
The answer is fairly straightforward - both blessings and curses are law! In fact they are the quintessence of law.
Law is: "If you... Then He'll..."
Gospel is "Since He... You are..."
Notice therefore that "If you... Then He'll..." is a message that could include curses or blessings. If you obey then He'll bless you. If you disobey, then He'll curse you. Whether the carrot is being dangled or the stick is being threatened the real issue is the phrase "If you...". What makes these messages law is not the curses or the carrots, it's the conditionality.
Both carrot and stick are law. And notice how Moses uses them. In Leviticus 26-27 (and in Deuteronomy) he outlines the potential blessings from Mount Gerazim and then the curses from Mount Ebal (of course he spends much longer on the curses!) By the time you get to Deuteronomy it becomes very obvious (see Deut 4 and Deut 30-34) that Israel will go into the curses of exile and only then attain to the blessings. Curses and blessings are not so much alternative possibilities but consecutive stages in their history.
Think how Jesus uses the blessings and woes in Luke 6. Blessed are those who have absolutely nothing. Cursed are those who think they have it made. Both sides of the coin uphold the one truth - we've got nothing, everything must come from heaven. In other words, it's all about the good law describing the good life that is entirely beyond us. Both the "positive message" of the blessings and the "negative message" of the woes are proclaiming our inability and God's all-sufficiency.
So let me draw a couple of points of application. First, there really is a shape to God's word. We know this supremely because God's Word is Jesus. And there's a shape to Jesus' life - down into the curses then rising into blessing. Certainly the little slice of Scripture we're reading might start with a "nice bit" and end with a "hard bit", but that slice of Scripture exists within a larger context. And if we're preaching, we're called to preach the larger context. We don't proclaim Luke 6:20-26, we proclaim Jesus from Luke 6:20-26. We never want to make the mistake of the Pharisees in John 5 - seeking life in the passage rather than the Person. If we preach the Person then we have to preach the pattern of that Person - a pattern that will be evidenced in the passage too, if we would only do our homework. But that pattern is down and then up, cross then resurrection, law then gospel.
Second, legalistic preaching (preaching law without gospel) is not always harsh-sounding preaching. It could be all about blessings, all about carrots, all about your best life now - if you.... If you only do this, or think that, or be the other - then you'll be blessed. Such a message might sound incredibly positive, but ultimately it's crushing because it's all about you.
Third, law-gospel preaching is not about balancing carrots and sticks. It's not about ensuring we play off the 'nice Scriptures' with the 'harsh ones' so that we're properly rounded. Some might be adept at sugar-coating some hard truths with some sweet verses. Others might temper their lovely promises with fearful warnings. But that is not law-gospel preaching - that is law-law preaching. "Christ is the end of the law that there may be righteousness for everyone who simply believes." (Romans 10:4)
Let's not leave our hearers in between Mount Gerazim and Mount Ebal. Let's take them on the journey that Scripture takes... through the curses into the blessings, through Golgotha and up to Zion. And let's make sure we preach Christ as the One who makes it happen.