Galatians 3:20

Now a mediator is not a mediator of one [ο δ ε μ ε σ ι τ η ς ε ν ο ς ο υ κ ε σ τ ι ν]. Observe,

1. De is explanatory, not antithetic. The verse illustrates the conception of mediator.

2. The article, the mediator, has a generic force : the mediator according to the general and proper conception of his function. Comp. the apostle (2 Corinthians 12:12); the shepherd, the good (John 10:11).

3. Enov of one, is to be explained by the following ei=v, so that it is masculine and personal.

We are not to supply party or law. The meaning is : the conception of mediator does not belong to an individual considered singly. One is not a mediator of his single self, but he is a mediator between two contracting parties; in this case between God and the people of Israel, as Leviticus 26:46; thus differing from Christ, who is called the mediator of a new covenant (Hebrews 8:6; Hebrews 9:15; Hebrews 12:24). The new covenant, the gospel, was not a contract. Accordingly verse 20 serves to define the true conception of a mediator, and through this definition to make clearer the difference between the law, which required a mediator, and the promise, which is the simple expression of God's will. The very idea of mediation supposes two parties. The law is of the nature of a contract between God and the Jewish people. The validity of the contract depends on its fulfillment by both parties. Hence it is contingent, not absolute.

But God is one [ο δ ε θ ε ο ς ε ι ς α σ τ ι ν]. God does not need a mediator to make his promise valid. His promise is not of the nature of a contract between two parties. His promise depends on his own individual decree. He dealt with Abraham singly and directly, without a mediator. The dignity of the law is thus inferior to that of the promise.