Our substitute, then, who took our place and died our death on the cross, was neither Christ alone (since that would make him a third party thrust in between God and us), nor God alone (since that would undermine the historical incarnation), but God in Christ, who was truly and fully both God and man and who on that account was uniquely qualified to represent both God and man and to mediate between them. If we speak only of Christ suffering and dying, we overlook the initiative of the Father. If we speak only of God suffering and dying, we overlook the mediation of the Son. The New Testament authors never attribute the atonement either to Christ in such a way as to disassociate him from the Father, or to God in such a way as to dispense with Christ, but rather to God and Christ, or to God acting in and through Christ with his whole-hearted concurrence.
John Stott, The Cross of Christ (Downers Grove: InterVarsity Press, 1986, 2006), p. 156.