The Council of Nicea (325 A.D.) stated the doctrine of the Trinity by clarifying the relations among the Father, Son, and Holy Spirit. It said that the three were of one substance "homoousios". However, it resolved nothing concerning the relationship between the divine and human aspects of Jesus Christ. This was to be left to the Council of Chalcedon (451 A.D.).
As was mentioned earlier, the Apostolic Kerygma implies both the humanity and divinity of Jesus. The Gospels affirm this. In Mark 15:39 and Matt. 27:54 we find- "Truly this was the Son of God". In Luke 23:47 we find - "Certainly this man was innocent".
The question for the church was and is - to what extent was the divine and the human in Jesus?
Tertullian (ca 200 AD.) wrote:
"The Son of God was crucified; I am not ashamed because men needs be ashamed And the Son of God died; it is by all means to be believed, because it is absurd. And He was buried and rose again; the fact is certain, because it is impossible." (ANF, Vol III, p 525)
The "fact" was not "certain" for everyone.
How can the Son of God die on a cross?
Docetists claimed that Jesus only "appeared" to have a physical body but that in fact he was a purely spiritual being. Of course, scripture affirmed that he was human because he ate, slept, and even wept.
Ebionism rejected the divinity of Jesus all together.
Others, called Adoptionists, focused on the humanity of Jesus to the exclusion of his divinity. He became divine only in the sense that God "adopted" him because of the exemplary life that he led.
Docetism, Ebionism and Adoptionism were all declared heretical by the early church because they did not conform with scripture.
Gnosticism rested on a secret oral tradition that had purportedly been transmitted by Jesus to followers during his forty-day appearance between the resurrection and the ascension. They acknowledged that the public tradition was legitimate but that there was more to it.
The conflict over this issue intensified following the decision at Nicea and it can be best understood by presenting the Christological views current at Alexandria and Antioch - the two great theological learning centers in the Middle East at that time. (The reference to Antioch or Alexandria as "schools" reflects a theological approach and attitude and not an actual school in the sense of a building, etc.)
Alexandrians had adopted a Logos-Flesh (or Word-Flesh) Christology. Their Christology began with the Johanine prologue which stated that "...the Word became flesh and dwelt among us, full of grace and truth ..." (John 1:14a).
In addition, Athanasius (c. 296-373), the champion of the Council of Nicea, had said "The Word of God... took a human body to save and help men, so that having shared our human birth, He might make men partakers of the divine and spiritual nature." (Placher, p. 80)
Apollinarius (c. 310- c. 390 A.D.) attempted to explain what this meant. In doing so, he brought all kinds of problems upon himself. He taught that Christ had a human body just like other humans have. However, he said that the Logos took the place of the human mind in Jesus.
Theodore of Mopsuestia (c. 350 - 428 AD.) a leading theologian in Antioch strenuously objected to this teaching. He said that Apollinarius was contradicting scripture for one thing. After all, the New Testament clearly stated that Jesus "grew and became strong, filled with wisdom" (Luke 2:40). The Logos is impassible. The human mind is not. Consequently, this reference from Luke proves that Jesus did indeed have a human mind.
Apollinarius responded by modifying his original stance. He said that the human mind consisted of two levels - 1) a lower one that experiences emotions and 2) a higher one that consists of reason. It was the higher aspect of the human mind that was displaced in Jesus by the Logos.
Theodore said that wouldn't do either. The Antiochene theologian was concerned with salvation. He replied that Jesus Christ saved humanity by uniting divinity with humanity. If not all of humanity is effected then complete salvation is impossible. If Jesus was not totally human then total salvation was not tenable.
Gregory of Nazianzus (329-389) expressed this argument in this way -
"If anyone has put his trust in Him as a Man without a human mind, he is really bereft of mind, and quite unworthy of salvation. For that which He has not assumed He has not healed; but that which is united to His Godhead is also saved." (Placher p 81)
The Council of Constantinople in 381 condemned Apollinarius' view. But the problem still wasn't solved. It was Antioch's turn to initiate controversy.
Nestorius (d. c. 451), patriarch of Constantinople in 428, accepted the two-natures Christology put forth by Theodore at the Council of Constantinople (381) in which he said that Christ had two natures (physeis) in one person (prosopon). Exactly what Theodore meant by this is unclear, but essentially he was trying to recognize both the humanity and divinity of Jesus. If Jesus wept, slept or ate, it was the human nature of Jesus doing so. Wherever there were miracles, or forgiveness of sin - then it was the divine nature of Jesus. In addition, each nature could be treated as a "subject" with "predicates" from the other (Communicatio Idiomatum). With this understanding, there was nothing wrong with saying that "Christ suffered". It is understood that the Logos of Jesus Christ is impassible and not subject to such.
Nestorius accepted all of this but he went one step further. He said because of this, it is wrong to call Mary, the mother of Jesus, "theotokos" ("bearer of God") because "being born" was something that happened to Christ's human nature and not to his divine nature. You could call Mary "Christotokos" or "bearer of Christ", however.
Cyril of Alexandria (d. 444 A.D.) objected. Nestorius had drawn such sharp distinctions between the two natures of Christ that it was difficult for Cyril to understand how they could be conjoined. Also, in terms of salvation, Nestorius' argument could be interpreted to mean that we are saved by a human being and not God. Consequently, a council met at Ephesus in 431 under the leadership of Cyril and Nestorius was condemned.
Cyril insisted on the communicatio idiomatum (the interchange of attributes) in dealing with the two natures but then he focused his attention on the oneness of Christ. This, taken to an extreme caused it's own problems after Cyril's death when Eutyches (c. 378 - 454) insisted that Christ had only one nature.
Dioscorus (d. 454), Cyril's successor as patriarch, took the offensive support of such monophysitism (one nature Christology) and presided over a council held at Ephesus in 449 and labeled the council of 431 the "Robber Council". He prevented any of his opponents from speaking during the debate and consequently stirred things up even further.
Finally, a council met at Chalcedon in 451. The decision reached rested in a significant way upon a letter or Tome written by Pope Leo I from Rome to the Robber Council which said in part:
"Without detriment therefore to the properties of either nature and substance which then came together in one person, majesty took on humility, strength weakness, eternity mortality: and for the paying off of the debt belonging to our condition inviolable nature was united with passible nature, so that, as suited the needs of our case, one and the same Mediator between God and men, the Man Christ Jesus, could both die with the one and not die with the other." (Petry, p 191)
Chalcedon (451) rejected Monophysitism and offered a statement which said in part:
"Therefore, following the Holy Fathers, we all with one accord teach men to acknowledge one and the same Son, our Lord Jesus Christ, at once complete in Godhead and complete in manhood, truly God and truly man, consisting also of a reasonable soul and body; of one substance with the Father as regards his Godhead, and at the same time of one substance with us as regards his manhood; like us in all respects, apart from sin; as regards his Godhead, begotten of the Father, before the ages, but yet as regards his manhood begotten, for us men and for our salvation, of Mary the Virgin, the God-bearer; one and the same Christ, Son, Lord, Only-begotten, recognized IN TWO NATURES, WITHOUT CONFUSION, WITHOUT CHANGE, WITHOUT DIVISION, WITHOUT SEPARATION..." (Bettensen,p 51)