From time to time I make new entries into this continuing series called “Theological Primer.” The idea is to present big theological concepts in around 500 words. Today we will look at the pactum salutis.
In simple terms, the covenant of redemption—or in Latin, the pactum salutis—refers to the eternal agreement between the Father and the Son to save a people chosen in Christ before the ages began. In slightly more detail, Louis Berkhof describes the covenant of redemption as “the agreement between the Father, giving the Son as Head and Redeemer of the elect, and the Son, voluntarily taking the place of those whom the Father had given him” (Systematic Theology, 271).
In traditional Reformed theology, the pactum has been a critically important doctrine, helping to make sense of (and hold together) election in Christ, God’s activity in history, and the intra-trinitarian love of God. It has also been a pastoral doctrine meant to give the believer confidence that because our covenant relationship with God has its origin in the Father’s pre-temporal covenant relationship with the Son, we do not have to merit our salvation but can rest secure in Christ our Surety.
Despite its central place in many of the best Reformed dogmatics, the pactum has often been criticized—both from without and from within the Reformed tradition. Three criticisms are most common.
First, it is argued that the pactum is sub-trinitarian in that no role is given for the Holy Spirit in the covenant of redemption. While it’s true that the pactum has normally been construed as an agreement between the Father and the Son, this need not undermine the Trinity any more than Jesus’ emphasis on the Father-Son relationship in the High Priestly Prayer undermines the Trinity. J. V. Fesko, in his excellent book on The Trinity and the Covenant of Redemption, has rightly defended the doctrine in more explicitly trinitarian terms, but even older theologians like Wilhemus à Brackel taught that “the manifestation of every grace and influence of the Holy Spirit proceeds from this covenant [of redemption]” (The Christian’s Reasonable Service, 1:262).
Second, others object that the pactum entails heterodox theology in that it undermines the singularity of God’s will. If the Father truly covenants with the Son, it is said, then the Father must have one will and the Son another. Reformed theologians, in anticipating this objection, have argued that the one divine will can be viewed from a twofold perspective. The Father and the Son have the same aim and objective, but whereas the Father wills to redeem by the agency of the Son as Surety, the Son wills to redeem by his own agency as Surety (cf. 1:252).
Third, and most critically, the pactum has been derided as metaphysical speculation. Barth famously dismissed the covenant of redemption as “mythology,” while more recently, an article in the Tyndale Bulletin argued that the pactum “lacks clear biblical support” and is little more than “scholastic tinkering” (69.2  p.281).
On closer inspection, however, there is good evidence in Scripture for a salvation pact between the Father and the Son. We know that the elect were chosen, not out of thin air, but in Christ before the foundations of the world. We know that promises were made to Christ that he would be given a people by the Father (John 6:38-40; cf. 5:30, 43; 17:4-12). We know that Christ, as the second Adam, is the covenant head of his people (Rom. 5:12-21; 1 Cor. 15:22). And we know from a text like Psalm 2 that there was a decree whereby the eternally begotten Son was given the nations as his heritage and the ends of the earth as his possession (v. 7; cf. Psalm 110). In other words, the Son was granted, by an eternal arrangement, a people to save and to redeem. This is why Zechariah 6:13 speaks of a covenant of peace between YHWH and the Branch, and why Jesus in Luke 22:29 speaks of the kingdom the Father has assigned to him. The covenant of grace in time is made possible by the covenant of redemption from all eternity.