Objective work of Christ
“Lutherans generally treat the doctrine of the mystical union anthropologically, and therefore conceive of it as established by faith. Hence they naturally take it up at a later point in their soteriology. But this method fails to do full justice to the idea of our union with Christ, since it loses sight of the eternal basis of the union and of its objective realization in Christ, and deals exclusively with the subjective realization of it in our lives, and even so only with our personal conscious entrance into this union. Reformed theology, on the other hand, deals with the union of believers with Christ theologically, and as such does far greater justice to this important subject. In doing so it employs the term ‘mystical union’ in a broad sense as a designation not only of the subjective union of Christ and believers, but also of the union that lies back of it, that is basic to it, and of which it is only the culminating expression, namely, the federal union of Christ and those who are His in the counsel of redemption, the mystical union ideally established in that eternal counsel, and the union as it is objectively effected in the incarnation and the redemptive work of Christ.”
(Louis Berkof, Systematic Theology, p. 447).
“He could merit salvation for them just because He already stood in relation to them as their surety and Mediator, their Head and Substitute. The whole Church was included in Him as her Head. In an objective sense she was crucified with Christ, she died with Him, she arose in Him from the dead, and was made to sit with Him in the heavenly places.”
(Louis Berkof, Systematic Theology, p. 448).