Two Natures in Christ.
There is a union. The elements united are the divine and human nature. By nature, in this connection is meant substance. In Greek the corresponding words are φοσις and οὐσία; in Latin, natura and substantia. The idea of substance is a necessary one. We are constrained to believe that where we see the manifestation of force, there is something, an objective entity which acts, and of which such force is the manifestation. It is self-evident that a non-ens cannot act. It may be well here to call to mind a few admitted principles which have already been repeatedly adverted to. (1.) It is intuitively certain that attributes, properties, and power or force, necessarily imply a substance of which they are manifestations. Of nothing, nothing can be predicated. That of which we can predicate the attributes either of matter or mind, must of necessity be a reality. (2.) It is no less certain that where the attributes are incompatible, the substances must be different and distinct. That which is extended cannot be unextended. That which is divisible cannot be indivisible. That which is incapable of thought cannot think. That which is finite cannot be infinite. (3.) Equally certain is it that attributes cannot exist distinct and separate from substance. There cannot be accidentia sine subjecto; otherwise there might be extension without anything extended, and thought without anything that thinks. (4.) Again, it is intuitively certain that the attributes of one substance cannot be transferred to another. Matter cannot be endowed with the attributes of mind; for then it would cease to be matter. Mind cannot be invested with the properties of matter, for then it would cease to be mind, neither can humanity be possessed of the attributes of divinity, for then it would cease to be humanity. This is only saying that the finite cannot be infinite. Speaking in general terms, in the whole history of human thought, these principles have been recognized as axiomatic; and their denial puts an end to discussion.
If the above mentioned principles be admitted, then it follows that in setting forth his Son as clothed in all the attributes of humanity, with a body that was born of a woman, which increased an stature, which was seen, felt, and handled; and with a soul that was troubled, joyful, and sorrowful, that increased in wisdom and was ignorant of certain things, God intends and requires that we should believe that He was a true man, — not a phantom, not an abstraction, — not the complex of properties without the substance of humanity, but a true or real man, like other men, yet without sin. In like manner when He is declared to be God over all, to be omniscient, almighty, and eternal, it is no less evident that He has a truly divine nature; that the substance of God in Him is the subject in which these divine attributes inhere. This being so, we are taught that the elements combined in the constitution of his person, namely, humanity and divinity, are two distinct natures, or substances. Such has been the faith of the Church universal. In those ancient creeds which are adopted by the Greek, Latin and Protestant Churches, it is declared that Christ as to his humanity is consubstantial with us, and as to his divinity, consubstantial with the Father. In the Council of Chalcedon, the Church declared our Lord to be,1Θεὸν ἀληθῶς καὶ ἄνθρωπον ἀληθῶς τὸν αὐτὸν ἐκ ψυχῆς λογικῆς καὶ σώματος, ὀμοούσιον τῷ πατρὶ κατὰ τὴν θεότητα καὶ ὁμοούσιον τὸν αὐτὸν ἡμῖν κατὰ τὴν ἀνθρωπότητα.
Thomas Aquinas says,2 “Humana natura in Christo quamvis sit substantia particularis: qui tamen venit in unionem cujusdam completi, scilicet totius Christi, prout est Deus et homo, non potest dici hypostasis vel suppositum: Sed illum completum ad quod concurrit, dicitur esse hypostasis vel suppositum.” In all the creeds of the Reformation the same doctrine is presented. In the “Augsburg Confession”3 it is said, “Filius Dei assumpsit humanam naturam in utero beatæ Mariæ virginis, ut sint duæ naturæ, divina et humana, in unitate personæ inseparabiliter conjunctæ, unus Christus, vere Deus et vere homo.” “Natura (φύσις, οὐσία) in Christo est substantia vel divinitatis vel humanitatis. Persona (ὑπόστασις, πρόσωπον) Christi est individuum ex utraque natura et divina et humana, conjuncta, non mixta, concretum.”4 In the “Second Helvetic Confession”5 it is said, “Agnoscimus in uno atque eodem Domino nostro Jesu Christo, duas naturas (for natura, substantia is used in other parts of the chapter), divinam et humanam… . . In una persona unitæ vel conjunctæ [sunt]: ita ut unum Christum Dominum, non duos veneremur: unum inquam verum Deum, et hominem, juxta divinam naturam Patri, juxta humanam vero nobis hominibus consubstantialem, et per omnia similem, peccato excepto.” Therefore the theologians teach,6 “Natura divina est essentia divina, qua Christus Patri et Spiritui Sancto coessentialis est. Natura humana est essentia seu substantia humana, qua Christus nobis hominibus coessentialis est.” Or as stated in the ancient creeds, Christ is not ἄλλος καὶ ἄλλος (one person and another person), but ἄλλο καὶ ἄλλο (one substance and another substance).