The Reformed understanding of the Communicatio Idiomatum (communication of properties) is that the divine and human natures are ascribed to the person of Christ without confusing or mixing of the two. For example, Christ can say that He has always existed with the Father in glory (John 17:5) because this is true according to the divine nature; even though the human nature was not eternal but brought into essence at His miraculous conception. The Lutheran view of the Communicatio Idiomatum is that, in some manner, the attributes of the divine nature are communicated, or given, to the human nature of Christ due to the majesty of the divine nature. This is called the Genus Maiestaticum. For example, Christ’s body is in, within, and under the Eucharist, because the divine property of ubiquity is communicated to Christ’s human nature. Louis Berkhof wrote a helpful 6-fold argument against this understanding of the Communicatio Idiomatum (1).
LOUIS BERKHOF’S ARGUMENT
1 – “It has no Scriptural foundation. If it is inferred from such a statement as that in John 3:13, then it ought also to be concluded from 1 Cor. 2:8 that the ability to suffer was communicated to the divine nature. Yet the Lutherans shrink back from that conclusion.”
Berkhof argued that if Lutherans were consistent they would need to deny divine impassibility. This doctrine teaches that the divine nature is incapable of suffering. The reason that it’s an issue to believe that God can suffer is if God can suffer, He can change. He would be reacting to an external influence outside of Himself and responding to it. He’d no longer be self-sufficient or independent because his existence and being would be affected by an external force. He’d no longer be all-powerful for the same reason. As Bavinck put it “This robs God of his divine nature, and religion of its firm foundation and assured comfort.” (Bavinck, Reformed Dogmatics, 2:158)
2 – “It implies a fusion of the divine and the human natures in Christ. Lutherans speak as if the attributes can be abstracted from the nature, and can be communicated while the natures remain separate, but substance and attributes cannot be so separated. By a communication of divine attributes to the human nature that nature as such ceases to exist. Omnipresence and omniscience are not compatible with humanity. Such a communication results in a mixture of the divine and the human, which the Bible keeps strictly separate.”
This could be considered to be a form of Eutychianism. This view, condemned at the Council of Chalcedon in 451 AD teaches that Christ was a confused mixture between the divine and human natures. As the Creed puts it Christ must “…be acknowledged in two natures, inconfusedly, unchangeably, indivisibly, inseparably; the distinction of natures being by no means taken away by the union, but rather the property of each nature being preserved, and concurring in one Person and one Subsistence, not parted or divided into two persons, but one and the same Son, and only begotten, God the Word, the Lord Jesus Christ;” Berkhof argued that applying attributes of one nature to the other is a mixture of the two. In this formulation, Christ’s human nature is dissolved through acquiring divine properties.
3 – “In the form in which the doctrine is now generally accepted by the Lutherans, the doctrine suffers from inconsistency. If the divine attributes are communicated to the human nature, the human must also be communicated to the divine. And if some attributes are communicated, they must also be communicated. But the Lutherans evidently do not dare to go the full length, and therefore stop halfway.”
The simple truth Berkhof shares here is that there is no true communication of properties if both natures aren’t affected. The obvious issue with being consistent at this point is that the divine nature would change, or cease if human properties were added. All that we are is derived from God, but not all that we are is in God. We share in some of His attributes through being made in His image (Albeit in a vastly limited capacity). We are relational because He is Triune, for example. However, He is omnipresent while we are locally present. He is self-sufficient while we rely on Him for everything. A self-sufficient being cannot take on properties from a contingent being without thereby becoming dependent on outside influences. The Communicatio Idiomatum cannot be consistently affirmed without working Christ’s humanity back into the divine nature.
4 – “It is inconsistent with the picture of the incarnate Christ during the time of His humiliation, as we find it in the Gospels. This is not the picture of a man who is omnipresent and omniscient. The Lutheran explanations of this inconsistency failed to commend themselves to the mind of the Church in general, and even to some of the followers of Luther.”
Christ didn’t know the time of His return according to His human nature (Matt 24:36). If there was a true communication of properties than Christ would have a share in the divine knowledge of everything. Appolonarius taught that Christ had a divine mind and was therefore omniscient. But again this would subsume Christ’s human nature because humans cannot contain all knowledge.
5 – “It virtually destroys the incarnation. Lutherans distinguish between the incarnatio and the exinanitio. The Logos is the subject only of the former. He makes the human nature receptive for the inhabitation of the fulness of the Godhead and communicates to it some of the divine attributes. But by doing this He virtually abrogates the human nature by assimilating it to the divine. Thus only the divine remains.”
Christ’s human nature ceases to exist if it gains divine properties. As the WSC states in Q/A 4 “God is a Spirit, infinite, eternal, and unchangeable, in his being, wisdom, power, holiness, justice, goodness, and truth.” A mixing of divine and human properties results in a new nature.
6 – “It also practically obliterates the distinction between the state of humiliation and the state of the exaltation. Brenz even says that these were not successive states, but states that co-existed during the earthly life of Christ. To escape the difficulty here, the Lutherans brought in the doctrine of the exinanitio, of which not the Logos but the God-man is the subject, to the effect that He practically emptied Himself, or laid aside the divine attributes. Some spoke of a constant but secret, and others of an intermittent use of them.”
The Kenosis theory is mentioned in passing by Berkhof. The Kenosis theory teaches that Christ emptied Himself of divine properties and functioned as a human on earth. Thereby the Logos wasn’t changed, but only the God-man. However, Orthodoxy teaches that the Son took on what He eternally was not, without ceasing to be who He always has been. The state of humiliation is necessary for salvation, as Hebrews puts it “For it was fitting that he, for whom and by whom all things exist, in bringing many sons to glory, should make the founder of their salvation perfect through suffering” (Heb 2:10). This isn’t possible if the divine nature is communicated to the human nature.
1 – All of these quotations were pulled from Louis Berkhof’s Systematic Theology page 308 – (Berkhof, Louis. Systematic Theology. Lexington, KY: CreateSpace Independent Publishing Platform, 2016.)