Defending the covenant of redemption (part three)

The present post is the third in a three part series addressing contemporary objections to the doctrine of the covenant of redemption (for parts one and two, see here and here). What follows is adapted from Michael Allen and Scott R. Swain, ed., Christian Dogmatics: Reformed Theology for the Church Catholic (Baker Academic, a division of Baker Publishing Group, forthcoming 2016). Used by permission.

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As I noted in my first post, some recent Reformed theologians worry that the covenant of redemption potentially undermines orthodox trinitarianism. Thus, Karl Barth asks, "Can we really think of the first and second persons of the triune Godhead as two distinct subjects and therefore as two legal subjects who can have dealings and enter into obligations one with another?" Robert Letham offers what he deems the inevitable answer to this question: "to describe the relations of the three persons in the Trinity as a covenant, or to affirm that there as a need for them to enter into covenantal--even contractual--arrangements is to open the door to heresy. The will of the Trinity is one; the works of the Trinity are indivisible. For all the good intentions of those who proposed it, the construal of the relations of the three persons of the Trinity in covenantal terms is a departure from classic Trinitarian orthodoxy." This is quite a charge! How should we respond?

It is important to observe that proponents of the doctrine of the pactum salutis long ago acknowledged and answered the tritheistic objection. So, for example, to the question of how it can be said "that the will of the Father and the will of the Son did concur distinctly in the making of this covenant," given the unity of God's will, John Owen responds: 

[S]uch is the distinction of the persons in the unity of the divine essence, as that they act in natural and essential acts reciprocally one towards another,--namely, in understanding, love, and the  like; they know and mutually love each other. And as they subsist distinctly, so they also act distinctly in those works which are of external operation... The will of God as to the peculiar actings of the Father in this matter is the will of the Father, and the will of God with regard unto the peculiar actings of the Son is the will of the Son; not by a distinction of sundry wills, but by the distinct application of the same will unto its distinct acts in the persons of the Father and the Son. 

Wilhelmus à Brakel addresses the issue in similar fashion: 

Since the Father and the Son are one in essence and thus have one will and one objective, how can there possibly be a covenant transaction between the two, as such a transaction requires the mutual involvement of two wills? Are we then not separating the persons of the Godhead too much? To this I reply that as far as personhood is concerned the Father is not the Son and the Son is not the Father. From this consideration the one divine will can be viewed from a twofold perspective. It is the Father's will to redeem by the agency of the second person as surety, and it is the will of the Son to redeem by his own agency as surety. 

In other words, when it comes to the relationship between the pactum salutis and the divine will, we must consider not only that will's unity and indivisibility, we must also consider that will's tripersonal manner of subsistence if we are to appreciate the doctrine's status as an instance of orthodox trinitarian reasoning.
 
Far from undermining orthodox trinitarian theology, therefore, the doctrine of the covenant of redemption should be seen as an application of orthodox trinitarian principles to the locus of God's eternal decree. Because the Son is consubstantial with the Father, God's redemptive will cannot be limited to the Father; the Son too must the agent of God's redemptive will. Moreover, because the Son eternally proceeds from the Father in his personal manner of subsisting, so too does his personal manner of willing proceed from the Father. The Son's willing submission to the Father in the pactum salutis is thus a faithful expression of his divine filial identity as the consubstantial, eternally begotten Son of God.