Likewise the Spirit helps us in our weakness. For we do not know what to pray for as we ought, but the Spirit himself intercedes for us with groanings too deep for words.  And he who searches hearts knows what is the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God.  And we know that for those who love God all things work together for good, for those who are called according to his purpose.  For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the firstborn among many brothers.  And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified. ( Romans 8:26–30 ESV)
“Our weakness” which receives the Spirit’s help, refers to the state of the not-yet-fully-and-finally-redeemed body (including material vessel and non-material mind and will) as we responds to the inevitability of suffering in a Fallen world. The weakened body groans under the weight of the effects of the Fall (in ways that might include our remaining propensities toward sin) despite our definitive regenerate condition.
The Spirit’s help is apparently in accord with God’s hidden will for us. By “hidden will,” I do not mean his will concerning our final state, for that has been declared outright--we will be glorified. But rather I reference the unrevealed means God will use to get us to that state. He who knows minds knows the mind of the Spirit and therefore “they” work in single accord. In this way, the Spirit’s intercession on our behalf advances the will of God toward our final conformity to Christ’s image (aka, “glorification” in this passage). “That Christ may be the firstborn among many brethren,” if it were marked for rhetorical emphasis would underscore the word “many” rather than “firstborn”--it is God’s will that the Firstborn (from the dead/in glory) should be joined by many additional brethren in the same state. So the Spirit intercedes in a way that accords with God’s will in order to guarantee that this will happen.
Again, I have said “hidden will” because the content of this intercession concerning our circumstances on our way toward this final state is unknown to us. We know this is unknowable because, first, we ourselves in our weakness cannot know how to pray according to God’s will (“we do not know what to pray for as we ought,” i.e., we do not know what will best progress us toward our destiny). Second, this intercession is described as containing “groanings which cannot be uttered,” which we should not take to mean that it is a contentless, emotional outcry. But rather “groanings” refers to the Spirit’s sympathetic understanding of our weakness, and “that cannot be uttered” refers to the inscrutable nature of their content. In other words, we are not privy to the content of this divine intercommunication, yet it is in perfect accord with God’s will, is specific to our suffering and weakness, and inexorably results in progress and advancement toward our destiny.
The point of Paul’s noting the inscrutability of the spirit’s help is to lay the foundation for what follows: No matter what happens in our lives as a result of the suffering that stems from the condition of our yet-to-be-glorified body in a fallen world, no matter how inscrutable it may be to our rationality, all that happens is guaranteed to be the result of the Spirit’s work to advance us toward our ultimate destiny of conformity to Christ’s likeness (“All things work together for good”). We may not be able to explain how or understand why something has occurred; the circumstances may leave us floundering in our weakness, struggling to deal, unable to see any good. Yet, we can be assured that “all things work together for good” for all those who are destined for glory. This is because God has decreed our destiny, according to his own eternal blueprint (his foreknowledge). The Spirit, knowing this destiny and what best serves this end, prays in a way that effects that destiny by means of all the parts of life in between, even when it involves suffering that prevents us from seeing how God will get us there.
Our comfort in this passage derives from knowing that our destiny is secure. Paul clearly lays out the ground of this assurance: First is the assertion that our destiny is determined, and nothing can prevent it. God knew beforehand exactly what he wanted to accomplish for every believer. His mind has drawn up the divine, eternal blueprint for our destinies (“foreknew,” foreknowledge). Second, God has sovereignly decreed to bring to pass all that is contained within that blueprint (“predestined,” predestination). He does all that pleases him. Third, he brings that decree to pass in time and space through effectual calling. Nothing can stand in the way of the Spirit’s work to regenerate predestined souls (“called”). Third, God has done all that is necessary within time and space to overcome the Fall--he justifies every predestined believer through the work of Christ, and in doing so, secures their destiny (Through the mechanism of the work of Christ, he declares them to be as righteous as Christ himself-- “justification”). Fourthly, the Father and Spirit work in perfect union to preserve and progress us in time and space (due to the Spirit’s intercession, “all things work together for good”) toward our eternal destiny (“glorified,” glorification; conformity to Christ’s image).
Yet another related element of comfort derives from knowing that the action of the Spirit on our behalf is sympathetic, personal, and concerned with every unique circumstance we face. The Spirit “groans” with us, showing he is fully aware of our weaknesses in the face of our suffering. The Spirit then intercedes according to the “will of God,” which means that he knows not only our destiny, but every perfect step in time and space that preserves and progresses us toward our destiny. The assurance that comes from knowing of and believing in this immediate and personal divine engagement is part and parcel of the comforting ministry of the indwelling Holy Spirit to every believer.
Yet another element of comfort derives from our knowledge and faith that inscrutable suffering is not in any way an obstacle to God’s purposes for us. In fact, God superintends the circumstances of our suffering as a result of the Spirit’s intercession to accomplish his purposes for us. They are the tools of God’s will whether or not we understand how and why. We are personally unequipped to navigate this suffering to get us there on our own, due to our weakness in a fallen world. How God uses this suffering to bring about our destiny may remain inscrutable to us (“cannot be uttered”). Yet the circumstances of suffering are, as they are worked out in accord with God’s will, exactly that which advance us toward glory through God’s protection, preservation, and proactive administration of “all things.” We are not only preserved and protected through the circumstances, but the circumstances are the very things through which God works for the good that is our destiny. We may never be privy to the answers we seek concerning our own suffering in this world, but through knowledge of and faith in these revealed truths, we can have patience, hope, and eagerness for what certainly awaits.