As I worked on my dissertation, one of the things that struck me was the importance of the covenant mediator for any covenant. Structurally, every covenant needs a mediator; and with regard to effectiveness, every covenant depends on the personal integrity of the covenant mediator (alternately called a federal head).
So for instance, in the first covenant Adam was the mediator and by his one sin, he led all of humanity into disobedience (Rom 5:18-19). Noah stands as the mediator of the Bible’s second covenant—a renewal of the original covenant. He is both effective in saving his family (and humanity) by obedience to God’s command, and his one act of sin—like Adam’s—reintroduced judgment into the human race.
As a covenant mediator, Abraham was blessed so that he might bless his offspring (Gen 12:1-3). He was not perfect—just ask Sarah his sister-wife—but his obedience on Mount Moriah did moved the promises of God from a covenant to the stronger position of a sworn oath. LIkewise, Moses stands as the prototypical mediator in Yahweh’s covenant with Israel (cf. Gal 3:19-20). Like the other mediators, he is a mixture of obedience and disobedience, faith and unbelief. In the end, his people crossed the Jordan River to enjoy God’s Promised Land, but sadly Moses did not. Last, David is the covenant head who received the promise of an eternal throne, but his sin and the sins of his children prevented them from experiencing the fullness of blessing (see the tension in Psalm 89).
Here is the main point: The strength of a covenant is dependent on the faithfulness of the one who mediates the covenant.
Throughout the Bible, this covenant reality poses a significant problem. From Adam to Abraham to David, no human mediator with is able to keep the covenant. Life is promised to those who maintain perfect righteousness (Lev 18:5), but no son of Adam ever kept the whole law. Hence, none of the covenants in the Bible secured shalom for God’s people. Of course, with the light of the New Testament, we know that this covenant disobedience was meant to stress the need for the perfect mediator—Jesus Christ, God’s own son. In him, and only in him, do we find someone who is able to both atone for the sins of the old covenant and effectively set up a new covenant by means of his priestly service and perfect sacrifice (see Hebrews 8-10).
While covenant mediation fails again and again in the Old Testament, the promise of an enduring covenant and the hope of perfect covenant mediator is held out in multiple places in Hebrew Bible. One of those instances is Daniel 9:26-27. Another is Isaiah 40-55, where the prophet speaks of the Suffering Servant as a covenant unto himself. What is striking in these verses is the way the servant of God not only ratifies a new covenant (notice the relationship between Isaiah 53 and 54-55), but is the embodiment of the covenant himself. Notice the language of Isaiah 42:6 and 49:8.
Isaiah 42:6. “I am the Lord; I have called you in righteousness; I will take you by the hand and keep you; I will give you as a covenant for the people, a light for the nations,”
Isaiah 49:8. Thus says the Lord: “In a time of favor I have answered you; in a day of salvation I have helped you; I will keep you and give you as a covenant to the people, to establish the land, to apportion the desolate heritages,”
Interestingly, in both of these passages which speak of the servant of the Lord, God says that he will not only make a new covenant as in Jeremiah 31. He says more simply: I will give you (speaking to the servant) as a covenant ‘for the people’ and ‘to the people.’ God’s point is to unite covenant and servant, such that the character and quality of the (new) covenant is directly dependent on the efficacious service of the servant.
This reading is confirmed by noticing how ‘covenantal’ Isaiah 53 is. While ‘covenant’ (berith) is not mentioned in that chapter, the covenantal blessings of Isaiah 54 and the new covenant features of Isaiah 55 flow from the work of the servant in Isaiah 53. In other words, by means of the sacrificial death of the servant, a new covenant is created. And this time, instead of it depending on fallible men; it depends upon the servant of the Lord who perfectly obeys the word of the Lord (see Isa 50:4-9).
In the end, Isaiah looks forward to the coming of Christ, and it affirms that when he comes, he will inaugurate a new covenant. And this covenant will be the final and effective covenant because it depends on his perfect obedience. This truth is explicated in Hebrews, but hundreds of years before Christ’s birth, the same plan of God was being foretold by the prophet Isaiah.
Soli Deo Gloria, dss