A special discussion of the communion of natures (communio naturarum) has become necessary because both the Reformed and the papists indeed admit a union of the human nature of Christ with the person (ὑπόστασις) of the λόγος, but deny the real and direct communion of the natures with each other. While they concede the unio personalis, they reject the communio naturarum. Their opposition to the latter doctrine, which Scripture teaches with great clearness, is based upon the rationalistic axiom: “The finite is not capable of the infinite.” Finitum non est capax infiniti. The Reformed theologian Danaeus writes: “Nothing whatever that is proper and essential to the Deity can in any way be communicated to a created thing, such as is the human nature assumed by Christ.” (Pieper, Christl. Dogmatik, II, 135 ff.) Insistence on this principle by Calvinistic theologians is so emphatic that they charge the Lutherans, who on the basis of Scripture affirm the communio naturarum, with Eutychianism, or the mingling of the two natures.
However, in denying the communio naturarum, the Reformed and the papists contradict and deny their own doctrine regarding the personal union. If the finite is incapable of the infinite, then indeed the union of human nature with the person of the λόγος (personal union) is impossible, since the person of the Son of God is as infinite as is His divine nature. In other words, then there can be no personal union. Then, too, the entire incarnation of the Son of God must be denied as impossible, since this consists essentially in the union of God with man. Hence consistency on the part of the Reformed and papists would demand the rejection of the entire mystery of godliness that “God was manifest in the flesh,” 1 Tim. 3, 16. The doctrine of the communion of natures follows directly from that of the personal union, so that they either stand or fall together.
But the Reformed and papistical error is directed also against Holy Scripture. The communion of the two natures of Christ is proved a) from general passages, such as John 1, 14; Heb. 2, 14. 15, etc., which clearly show that the Son of God so joined Himself to the flesh (σάρξ) that His divine nature has true communion with the human nature; b) from special passages, such as Col. 2, 3. 9: “In Him dwelleth all the fulness of the Godhead bodily” (σωματικῶς). From these passages we learn in particular:
a) That the divine nature entered into a true and real union with the human nature, since the fulness of the Godhead dwells in Christ bodily. On the basis of this and other passages, Hollaz writes: “The communion of natures in the person of Christ is the mutual participation of the divine and human natures of Christ, through which the divine nature of the λόγος, having become participant of the human nature, pervades, perfects, inhabits, and appropriates this to itself; but the human nature, having become participant of the divine nature, is pervaded, perfected, and inhabited by it” (Doctr. Theol., p. 316 ff.);
b) That in Christ there is not mere contiguity (συνάφεια) of the two natures, but a most profound and intimate interpenetration (περιχώρησιςλ), since the divine nature permeates the human nature, just as the soul permeates the body;
c) That in spite of this most intimate interpenetration there is no mingling, mixture, or change of the two natures, because the fulness of the Godhead dwells in the human nature. As the persons of the Trinity permeate each other without mixture, or as the soul dwells in the body without mingling, so the λόγος pervades the flesh in such a manner that neither of the natures is mingled or mixed with the other (unio ἀσύγχυτος, ἄμικτος, ἄτρεπτος);
d) That the divine nature must not be conceived as extending beyond the human, since the fulness of the Godhead dwells in the body. In other words, just as the soul is in the living body, but never beyond it, so the λόγος is in the flesh so as never to be beyond or outside it (neque caro extra λόγον, neque λόγος extra camera);
e) That the communion of the two natures in Christ is inseparable (ἀχώριστος), since they are united permanently (ἀδιαστάτως), or so that they are always mutually present to each other. The doctrine of the communion of natures as taught by the Lutheran theologians is therefore truly Scriptural.
Quenstedt presents the doctrine as follows: “The communion of natures is that most intimate participation (κοινωνία) and combination (συνδύασιςof) the divine nature of the λόγος and the assumed human nature by which the λόγος, through a most intimate and profound interpenetration (περιχὠώρησις), so permeates, inhabits, and appropriates to Himself the human nature personally united with Him that from both, mutually intercommunicating, there arises the one incommunicable subject, namely, one person.” (Doctr. Theol.j p. 310.) The opposing Zwinglian doctrine (Nes- torianism) Quenstedt describes as follows: “We condemn the antithesis of the Calvinists, some of whom teach that it is only the person of the λόγος and not at the same time His divine nature that has been united with human nature. . . . Thus they invent a double union, mediate and immediate, saying that the natures are united, not immediately, but through the medium of the person of the λόγος.” (Doctr. Theol., p. 316.)
The Reformed theologians object to the communion of natures on the ground that in that case the human nature of Christ must be conceived of as being “very large,” since otherwise it could not be everywhere present with the divine nature (local extension); indeed, that in that case it could not be regarded as a true human nature at all, since properties are ascribed to it of which human nature is incapable. In answer to this we say that the human nature of Christ was not physically enlarged through the incarnation, but is omnipresent with the divine nature. Matt. 28, 20, not by local extension, but by an illocal mode of presence, John 20, 19—26; Luke 24, 31, which it possesses besides its ordinary local mode, John 4, 3. 4, by virtue of the personal union.
If the Reformed theologians furthermore ask how this is possible without the destruction of the human nature, we answer that Holy Scripture teaches this to be a fact (John 1,14; Matt. 28, 18—20), though a great mystery (1 Tim. 3, 16), and that therefore this doctrine must not be denied, but believed. Again, if they affirm that the human nature of Christ received extraordinary finite gifts (dona finita extraordinaria), but not truly divine gifts (dona divina), we remind them of the Scripture- passages which directly ascribe divine gifts to the human nature, 1 John 1, 7; Matt. 9, 6; John 5, 27; Matt. 28, 18. 20. While the human nature performs actus naturales (eating, drinking, suffering, dying, etc.) which are common to all men, it performs also actus personales (forgiving sins, executing judgment, etc.) which are the direct result of its intimate communion with the divine nature.
As the personal union, so also the communion of natures is proved by such personal propositions as “God is man” and “Man is God”; for these propositions predicate a real communion of the natures in Christ. To the objection of the Zwinglians (Nestorians) that the personal propositions, so far as the communion of natures is concerned (quoad communionem naturarum), are only nominal (propositiones verbales, propositiones tropicae), we reply that in that case also the incarnation, the personal union, and the entire doctrine of Scripture concerning the person of Christ must be regarded as nominal or figurative; for what is true of a part of a mystery is true of the whole of it. Indeed, if we must regard as nominal or tropical in Scripture everything to which man’s blind reason opposes itself, then, in the last analysis, every article of faith must be denied.
Against Eutychianism and Nestorianism the Formula of Concord (Art. VIII, 13 ff.) declares: “The two natures were united not as two boards are glued together, so that they realiter, i. e., in deed and truth, have no communion whatever with one another” (against Nestorius and Samosatenus), nor by “a mixing or equalizing of the natures, as when hydromel is made from honey and water, which is no longer pure honey and water, but a mixed drink” (against Eutyches), but as “the soul and body, and fire and iron, which have communion with each other, not by a phrase or mode of speaking or in mere words, but truly and really.”
Against the errors of the Calvinists (Nestorians), papists, and Eutychians our dogmaticians have in summary described the permeation of the two natures (περιχώρησις) as follows: It is a) intima et perfectissima, intimate and most perfect; b) mutua, the divine nature permeating the human and the assumed flesh being completely permeated by the divine nature; c) inseparabilis (ἀχώριστος); d) without confusion, mingling, or changing (ἀσύγχυτος, ἄμικτος, ἄτρεπτος), yet so that the two natures of Christ are united continuously (ἀδιάστατοι, sive sibi mutuo praesentes) and are never outside each other (nuspiam ultra, nuspiam extra).