This essay will explore an explanation to resolve the theological contradiction in saying that the Church (the Body of Christ) has a preexistent nature (i.e. ‘there was never a time when the Church did not exist’) against the reality that the Church is a created thing and not a person with selfhood.
The communication of idioms (comunicatio idiomatum) means that whether we are speaking of the historical person Jesus of Nazareth or of the Begotten Son of God or of the Divine Word, we affirm, concretely, that we are speaking of the same person because the nature of one is the same as the other; therefore, all of the concrete terms for the Son can be used interchangeably for the same person. That is, the apparent contradiction of both the subject and the predicate of the sentence in the comunicatio idiomatum are resolved by the Hypostatic nature of Christ Jesus.
The Three Limitations of the Comunicatio Idiomatum
Historically, this communication of idioms in regards to oneness of the one person subsisting in the two natures of Christ Jesus is not something tradition has applied to the other persons of the Holy Trinity or to the Church. The reason for that is because we have not needed to have a comunicatio idiomatum for the Father or for the Holy Spirit, simply because their Divine natures are not hypostatically united with a human nature or any other nature. Nor can it apply to all three persons of the Holy Trinity, because only one of them has a human nature. For example, we cannot say that the Holy Trinity was crucified, died, and was buried, but we can say that about the concrete names applied to the Christ Jesus. In this way, communication of idioms in Catholic theology are limited only in reference to the Second Person of the Holy Trinity.
The second limitation can be proposed with the question: What about those who are uniquely in Christ Jesus, such as a priest who is uttering the holy words of consecration during the Sacrifice of the Mass? Can the communication of idioms be applied to Christ and His priest in such a way that when we speak of one, we are speaking of the other? The answer to that question is an emphatic ‘no’. Why? Because at no time during the life of the priest does his nature become hypostatically one with the nature of the Son. The nature of the priest remains always the nature of the priest and never the nature the Divine Son.
The final limitation of the comunicatio idiomatum supports the argument for this First Historical Mark. We cannot speak of the comunicatio idiomatum in reference to the Church, first because the Church does not have a nature of its own, inasmuch as it lives in and by the preexistent nature of God; and second, because the Church does not have personal selfhood, despite the fact we have traditionally potentially clouded that fact by calling it ‘She’.
How the Church is a Person with Personal Selfhood
The position put forth here, that the Church is without personal selfhood, is distinct from the proposition that the Church is a person, and it should be clarified before proceeding further; for, there is a language by which we can call the Church a person. The traditional philosophical idea of personhood in regards to human being resolved around terms of “certain independence in being and acting.” For ancient Roman law, persona est sui iuris et alteri incommunicabilis (“a person is a being which belongs to itself and which does not share its being with another”); for Saint Thomas Aquinas, a person has an “individual substance” with a rational nature of its own; for Immanuel Kant, each person is an end in himself. Crosby rounds these traditional ideas into the aspects of personhood being 1) unrepeatable and incommunicable, and 2) subjective (i.e. “only acting through themselves and living in freedom do they come alive subjectively”). It would seem that none of these three characteristics of a person can be applied to the Church.
It is true that the Body of Christ, which is many belonging to the One, cannot possibly be a person per the above mentioned traditional standards, because it lacks a selfhood, substance and nature of its own, nor does it act independently according to itself, communicate itself, or is an end in itself. Rather, it acts in union with the many, participates in the nature of God, and communicates and belongs to Christ Jesus. Yet, it is in that plurality of the many subsisting in the One that Benoit-Dominique considers the Church as a person or having a “personality”, “The Church is a reality that is one, undivided, individual,” and it is in this that the Church fulfills the “first criterion for being a person.” Crosby also finds that only in God does the personhood and moral goodness of the plurality of human beings find their perfection. Outside of God, they are finite and limited, but in the person of God, they find their fullness their personhood.
This process of becoming whole by being plurally incorporated into God seems to be consistent with St. Augustine’s definition of the personhood of God, which is “predicated plurally of the Three in contrast to the nature of the names belonging to the essence.” God, who is plural in nature, draws a community into Himself so that they might be like Him.
Now, returning to the final limitation of the comunicatio idiomatum; while there is never an opportunity to concretely mean the person of Christ Jesus and His self-hood when we are speaking of His Church, there also is never an opportunity to not speak of Christ Jesus when we are speaking of His Church, because it truly is His Mystical Body, and it truly does, through the work and co-mission of the Holy Spirit, participate in His Divine nature more closely than any other created thing.
This close union between Christ and His Church imposes on us the restriction of not speaking of one without speaking of the other. The union of the Christ and His Church is not a hypostatic union between the two natures in the Church, but it is a union that is so intimate and so close that when one is persecuted the other is as well; and when one is listened to the other is as well. The Divine and human natures that compose the Church are so definitively and imperfectly unified, through the work and mission of the Holy Spirit across space and time, that we can use the comunicatio idiomatum as a way to say that where the Son is, so too is His Church.
 Crosby, John F. The Selfhood of the Human Person. Washington, D.C.. The Catholic University of America Press. 1996. 1. Print.
 S.T., I, Q. 29, art. 1.
 Crosby, 1.
 Crosby, 83.
 de La Soujeole, Benoit-Dominique. Introduction to the Mystery of the Church. The Catholic University of American Press. Washington D.C. 2014. 507. Print.
 S.T., I, Q. 29, art. 4.