"Jesus -- The Messianic Heir, the True Adam and Israel" -- Horton on the Person of Christ
Why the Birth of the Savior?
All of God’s covenantal purposes converge in Jesus Christ. The Son is the eternal Mediator of the covenant of redemption which already in eternity rendered him, by anticipation, the one who would become incarnate and give his life for his people (1 Pe 1:20–21; Eph 1:4–5, 11). He is also the Last Adam, who undoes the curse of the first Adam and fulfills the covenant of creation for his elect, thereby winning the right to be not only the risen head but the resurrection-life-giving Lord. Therefore, the covenant of grace of which Christ is the mediatorial head is secured eternally in the covenant of redemption. “ For all the promises of God find their Yes in him” (2 Co 1:20).
Although Israel, like Adam, failed to drive the serpent out of God’s holy garden and instead succumbed to the seduction of God’s archenemy, God pledges that he will not utterly destroy Israel but will preserve a remnant from which will emerge the Messiah who will bring an ultimate salvation and an everlasting kingdom of righteousness not only to Jews but to the nations. If the works principle inherent in the Sinai covenant stood alone, neither Israel nor the world would have any hope.
Yet even in its exile, Israel too is given the promise that its coming Shepherd will gather his scattered sheep and bring redemption to the ends of the earth. The enlargement of Jerusalem promised with the new covenant in Jeremiah 31 and 32 is anticipated elsewhere, sometimes in passages that even recast the traditional roles of the oppressor (Egypt and Assyria) as the oppressed who are delivered from bondage and taken as God’s own people (Isa 19:18–23). Isaiah 60 sets before us the vision of ships from all over the world entering Israel’s harbor, laden this time not with implements of war but with rich treasures. “Nations shall come to your light, and kings to the brightness of your rising” (v. 3). A royal procession of the nations and their kings, into gates that never close (v. 11), echoes the Sabbath enthronement of God in the beginning, with the parade of the creature-kings before the Lord in the day-frames of Genesis 1 and 2. Psalm 2 evokes the courtroom scene, with the creature-kings arrayed before the Sabbath splendor of the Great King and his anointed one (Messiah), but in war rather than tribute, with the Great King laughing at the self-confident posturing of the earth’s rulers who reject the Messiah, yet promising salvation from this coming judgment for “all who take refuge in him.”
Michael Horton, The Christian Faith: A Systematic Theology for Pilgrims on the Way (Grand Rapids, MI: Zondervan, 2011), 446-447.