The other problem we will have to avoid is in saying that the essence of God underwent any change whatsoever in the Incarnation. Here the Chalcedonian formulations help us out. The two natures of Christ remain distinct, even though inseparable. Therefore, the divine nature of Christ did not change at all when the Son added a full human nature to Himself.

One of the most difficult questions in Trinitarian theology is how the essence/person distinction relates to the Incarnation. The classic formulations state that God is in essence one, and that one essence is shared fully and completely in the three persons of Father, Son, and Holy Spirit. The essence of God must be involved somehow in the Incarnation, but finding a way of expressing that is difficult. On the one hand, it is vitally important not to drive a wedge between the essence of God and the three persons. Otherwise, we wind up with the classic problem of a quaternity (essence plus three persons).

The way this problem has been avoided in the past is through the doctrine of perichoresis, or mutual indwelling of the persons. The three persons interpenetrate each other in such a way that the persons remain distinct, and yet share fully in the essence. Perichoresisis also the only resource we have for understanding how God can be one essence that is simple (not divisible), and yet also be three distinct persons.

Objections to this doctrine usually bring God down to man’s level. For instance, someone will object that an essence cannot be so shared. The objection will only prove true, however (upon close examination), of mortal and finite essences. An infinite essence such as God’s essence is not limited by such problems.

The other problem we will have to avoid is in saying that the essence of God underwent any change whatsoever in the Incarnation. Here the Chalcedonian formulations help us out. The two natures of Christ remain distinct, even though inseparable. Therefore, the divine nature of Christ did not change at all when the Son added a full human nature to Himself.

This helps us answer the question: did God’s essence become incarnate? We have to say that God’s essence did not change into something else at the Incarnation. At the same time, we have to say that God’s essence was involved in the Incarnation. The Reformed scholastics help us out here. Their formulation is that God’s essence is incarnated, but only in one of its hypostases or persons (see Richard Muller, Post-Reformation Reformed Dogmatics, volume 4, p. 211). The process of incarnation is one of addition. A full human nature is added, taken up in hypostatic union with the second person of the Trinity, the essence of God in the second person. This must not be understood in any way that would imply that a separate already-formed human person was joined to the divine person. The full human nature (body and soul) of Christ only ever exists in hypostatic union with the divine nature. This being said, the Father and the Holy Spirit were not passive spectators in the Incarnation either. All the outside works of the Triune God are indivisible (which means that all three persons of the Trinity are at work in everything God does). The Father sent both the Son and the Spirit in the process of incarnation, and the Holy Spirit overshadowed Mary. This must qualify what was said about only the second person being incarnated. For while it is true that only the second person became incarnated, yet it is also true that the Father and the Holy Spirit were involved.

Lane Keister is a minister in the Orthodox Presbyterian Church and is pastor of Momence OPC in Momence, IL.  This article is used with permission.