Regenerate believers who take Christology seriously know that the Chalcedonian formulation—two natures united in one person—is not a doctrine of adiaphora; it is an essential doctrine of the Christian faith. It is necessary to everlasting salvation that one rightly believes that Christ is homoousios (homo: same + ousios: substance) with the Father and is one person or hypostasis who has two distinct, unmingled, and inseparable natures.

The Council of Chalcedon (451) repudiated several heresies that attacked the deity of Christ, such as Eutychianism, Apollinarianism, and Nestorianism. Mainly, the controversies were concerning the person of Christ and his two natures. Thus, the Chalcedonian Creed undeniably and unequivocally teaches that Christ is God of the substance of the Father, and although he is wholly God and wholly man, he is not two, but one person. Take the time to examine the Chalcedonian Creed.

We, then, following the holy fathers, all with one consent teach men to confess one and the same Son, our Lord Jesus Christ, the same perfect in Godhead and also perfect in manhood; truly God and truly man, of a rational soul and body; coessential with the Father according to the Godhead, and consubstantial with us according to the manhood; in all things like unto us, without sin; begotten before all ages of the Father according to the Godhead, and in these latter days, for us and for our salvation, born of the Virgin Mary, the mother of God, according to the manhood; one and the same Christ, Son, Lord, Only-begotten, to be acknowledged in two natures, without confusion, without change, without division, without separation; 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; as the prophets from the beginning have declared concerning Him, and the Lord Jesus Christ Himself has taught us, and the creed of the holy fathers has handed down to us. (Creed of Chalcedon, in Confessions and Church Order, 17)

Rejecting the historic Chalcedonian definition of the hypostatic union, which refers to the combination of Christ’s two natures in one person, is a foul heresy. One such attack on the divinity of Christ is called Nestorianism. This heresy opposes what was confessionally established at Chalcedon: “the property of each nature being preserved, and concurring in one person.” Put another way, the crux of the issue surrounding Nestorianism is that it maintains that Christ is not one person but is two distinct persons or hypostases. 

Nestorianism derives its name from Nestorius, a patriarch of Constantinople from 428–31. Nestorius’ Christology was called into question and scrupulously interrogated because he believed that Mary should be called the mother of Christ (Christotokos; Christ-bearer) and not the mother of God (Theotokos; God-bearer). This was due to the fact that Nestorious, like many today, failed to comprehend the hypostatic union, which teaches that the divine Logos σὰρξ ἐγένετο (“became flesh”) and is truly God and truly man, not divided into two persons, but one and the same Son and only begotten, God the Word.

Nestorious was not able to palliate his teachings that Mary was the mother of Christ, not the mother of God, or that Christ was two persons, not one. Nestorius’ views on Christology were not only anathematized at the Council of Ephesus (431) but were also condemned as heresy at the Council of Chalcedon (451). Consequently, the Creed of Chalcedon states that Christ was “born of the Virgin Mary, the mother of God”; and regarding his two natures, it teaches, “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” (emphasis mine).

Even though Nestorianism was condemned as heresy centuries ago, there is a proliferation of professing Christians in the twenty-first century who regard Nestorianism as a trivial matter or a tertiary doctrine that can be overlooked so long as the one propagating the two-person heresy (that is, Nestorianism) is popular. This is due to the fact that many are ignorant about the tri-personality of God, Christology, and church history, or they simply don’t care that the doctrine of the person of Christ is maligned. Examine the following three ways to avoid being deceived.

First, Nestorianism is regarded by many scholars as a polysemic term; therefore, Christians should not be surprised when Nestorians are ambiguous or inconsistent in defining their terms. Nonetheless, the crux or the underlying issue of the Nestorian heresy is that it teaches that Christ’s deity and humanity were divided and split into two distinct persons living in one body. This is the heresy of Nestorianism that must be rejected.

Second, most modern-day heretics who teach a two-person Christ will deny being Nestorians, in the same manner that most heretics will not admit that they teach heresy. Even Nestorious denied that his two-person Christ dogma was erroneous, as many will do today. Therefore, just because one says he is not a Nestorian, Christians should never hastily exonerate him of heresy unless he unashamedly rejects the Nestorian heresy, which taught that the incarnate Christ was two persons, one divine and one human.

Third, don’t be duped by Nestorians, either admittedly or not, who try to redefine the meaning of person in order to maintain their two-person heresy. A person is an individual hypostasis that says “I” and is a moral and rational subsistence that can be distinguished by personal properties. The Bible will concur. For example, the Holy Spirit is called “he” in John 16:13, and the Holy Spirit says “me” and “I” in Acts 13:2. In John 14:26 Jesus spoke in the first person (“my”) about the Holy Spirit and spoke about the Father in the third person. Additionally, the Bible teaches that the Spirit loves and has fellowship (Rom. 15:30;
1 John 1:3); the Spirit commands (Acts 10:19–20; 13:2), and the Spirit grieves (Eph. 4:30). All three persons of the Godhead can be distinguished by their personal properties: the Father is neither begotten nor proceeding; the Son is eternally begotten of the Father before all ages (not made or created); and the Spirit proceeds from both the Father and the Son.

Therefore, if you meet a Nestorian or read about one who is adamant that previous theologians throughout the church did not properly define the word person, don’t be duped by his philosophical claptrap but realize that his argument does not prove the point he has tried to make; all his argument proves is that he does not like what has been confessionally established and taught throughout scripture. Christ is never regarded as two persons in the Bible, and albeit he is both truly God and truly man, he is not two persons but one person, and he is completely one in the unity of his person, without confusing his natures.

In closing, this article has explained that it is necessary to everlasting salvation that one rightly believes in the person of the Son and why Nestorianism is heresy. The controversy surrounding the completeness of Christ’s two natures was settled at the Council of Nicea in 325 and Constantinople in 381, and as previously mentioned, Nestorianism was condemned as heresy at the Council of Ephesus in 431 and at the Council of Chalcedon in 451. Therefore, don’t be duped by this heresy that was condemned long ago.