This is part of my series thinking through the sermon on the mount in particular in relation to Pennington's book on it. (Posts 1, 2, 3, 4)
How do you sum up the Torah, interpreted through the Prophets? Jesus' famous, memorable, significant, penetrating, and climactic statement does a pretty decent job: In relation to all things, that which you would others do unto you, so you also do unto others; for this is the Torah and the Prophets.
The Golden Rule is not unique. Not exactly unique among world religions, not unique in the Bible. But it is breath-taking in its simplicity and in it what it offers us. We can consider it's inverse, which is the Rule of Vengeance : "that which others do (or even would do) to you, do unto them". If that is our basis for behaviour in the world, and for some many people it is, we are in an inevitable spiral to repay evil with evil, suffering with suffering, wrong for wrong. There is only one way to halt that spiral, subvert the cycle of vengeance, and that is to choose to bear an evil suffered with costly grace, and repay it with good. To act with grace towards others just as we might hope they will act with grace towards us, even when they don't, won't, and maybe never will. The Golden Rule isn't predicated on outcomes and results, it's not a calculation that if I treat you nicely, you will treat me nicely. It's a commitment to be the kind of person who will act for your whole-hearted welfare and good, whether you respond in kind or not.
And starting here in 7:12 helps to make sense of 7:1-11 as well. Whereas 6.19-34 focuses on "Greater Righteousness in relation to [the things of] the world", 7.1-12 is about "Greater Righteousness in relation to the people of the world". Pennington recognises and struggles with the fact that this section of the Sermon seems the hardest to 'tie together' thematically and structurally, but I think he does a good job. He takes the leading verse as thematic for "evaluating or discerning correctly", and notes the problems with how we translate and understand 'judge'.
In most translations 7:1 is rendered something like, "Do not judge so that you not be judged". Two problems immediately arise. Firstly, 'judge' in contemporary English tends to bear a restricted sense of 'condemnation'. But the Greek has a broader range (just as the English can have a broader range), referring to evaluating, discerning, deciding, coming to a right and accurate judgment about a matter. It is about discerning what is right/just, and then seeking to enact or render or deliver justice.
This gets us out of the trap of those who want to totalize the verse to "well, Jesus says don't judge, we so don't judge or condemn anyone, and if you are condemnatory, you are condemned"; I mean, it's clear even within the SotM that Jesus is prepared to condemn a lot of things (not least hypocrites!). The parallelism of v2 reveals the sense of v1 - we ought to expect to be measured (= evaluated/judged/treated) with the same measure that we extend to others. This is the same principle that's applied specifically to forgiveness back in 6:12, 14-15 - we ought to forgive with a forgiveness modelled on the divine forgiveness of the Father to us, and when we don't we are in effect declaring that we'd rather that God dealt with us and our sins on the basis of how we treat others who sin against us.
And so we can read 7.1-2, and 12 as the general extension of that principle : how God does treat us shapes and forms how we should treat others, and how we do treat others expresses how we think God should treat us. If we truly, deeply, comprehensively grasp and receive the profound gracious mercy and compassion of God to us, it will whole-heartedly transform how we treat others - in that same way. Which is what the example in v3-5 is doing: teaching us how hard it is to evaluate correctly, because we evaluated others more harshly than is proper, and ourselves more lightly.
Verse 6 is difficult, as everyone agrees. I'll just leave you here with Pennington's paraphrase "Do not toss your teaching to outsiders, lest they scornfully reject it and you.”
7-11 does not appear immediately connected to the proposed theme of this section, but I think it can be tied in this way - the grounding of the encouragement to prayer here is the kindness of the heavenly Father, (Pennington says as much) and what I would add is that the way that treatment of others relates to both God's treatment of us, and our expectation in return of God's treatment of us, interweaves between these three poles of God, me, others, so that just as God's gracious and good and trustworthy kindness is the grounding for my treatment of others, so too it is the basis for prayer. I am to treat others on the basis of God's character and way of being, and likewise I ought pray to God with an expectation of his good gifts on that same basis.
And then, I should take the Father's generosity in giving to me, to give to others, and his mercy in forgiving me, to forgive others, and his grace to me, to extend grace to others in all areas of life.