Jer. 30:12-13,15,17 — “Your hurt is incurable, and your wound is grievous…[there is] no medicine for your wound, no healing for you…Your pain is incurable.” /// “…*I will* restore health to you, and your wounds *I will* heal.”
The wound referenced here the wound of and the wound dealt by YHWH’s people’s turning from Him (22:8, etc.). In other words, it is sin—opposition to the character of God, chiefly manifest in turning to what is not God as god (c.f., 30:14-15). Sin, then, is the wound that cannot be healed, the wound that is incurable and for which no medicine exists. How can YHWH promise to restore health to such an irretrievably wounded people? How will He heal the wounds that are beyond healing?
The answer implied in the rest of Jer. 30 is the return from exile. The problem is, when the people returned from exile in Babylon, they still bore the wound of YHWH-opposing sin. The only difference is that it had sunken below the skin and now resided deep in the heart, where idols were set up before the soul’s affections rather than before the body’s eyes. So the wound was not healed. How, then, would it be?
Ultimately, the incurable wound of the human soul is cured only as YHWH Himself in Jesus Christ bears that wound in His own human soul. Only as the Messiah—Jesus, True Israel and True Humanity—receives in Himself the incurable wound of His people, and endures in Himself the True Exile of damned death, and from the depths of that Exile is raised up again, restored to the land of the living (the land that lives because He Himself is the Living One), and so becomes the Truly Restored and Truly Healed People of God, only in this way are the wounds of God’s people healed, is the exile of God’s people overcome, is the incurable sickness of God’s people fully and finally cured such that they might truly be His people and He might truly be their God. Only in the crucified and risen Jesus—whose death is the exile of His people under the incurable wound of their sin and whose resurrection is the return of His people to the land of the living and the reconciled presence of YHWH—only in Him is the incurable cured and that which is beyond healing healed.