Apollinarianism is the belief that Christ does not possess a human spirit as we do, but that it was replaced by the divine Logos. This teaching is named after Apollinarius, bishop of Laodicea. Apollinarius held to a trichotomist view of the nature of man. Man is divided into a physical body, a spirit or rational soul which acts as the mind of man and is unique to humans, and a lower soul which animals share in as well. He believed that while Christ had a human body and a human lower soul, he did not have a human spirit, rational soul, or mind as we do. He came to this conclusion as a result of trying to reconcile the truth that Jesus is impeccable or unable to sin with the truth that he is truly human. He reasoned that in order for Jesus to be unable to sin, he could not have a human spirit as we do. The result of this belief, just like monophysitism and monotheletism, is that Jesus is less than fully human because he does not possess a human spirit or mind as we do. But like these other views which tend toward docetism, they contradict the truth of Hebrews 2:17 which teaches us that the Son had to become like us in every way in the incarnation: “Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.”
This belief is actually a relic of Arianism which holds to an Apollinarian-like understanding of the person of Christ. They believed that the Logos dwelled in the man Jesus Christ and was distinct from him. Jesus has a human body without a human soul because the Logos takes its place (Richard A. Norris Jr., The Christological Controversy, 15). This composite Logos-flesh view of Jesus where he is composed of both a body and the Logos who indwells him served as a precursor for the Nestorian understanding of Jesus. In Arianism, the Logos is not the same as the man Jesus Christ who is flesh, but is a lesser deity who dwells inside him. The irony of this is that Apollinarius was an opponent of Arianism who affirmed that the Son is truly God.
Pope Damasus I at the Council of Rome in 382 condemned Apollinarianism:
“We pronounce anathema against them who say that the Word of God is in the human flesh in lieu and place of the human rational and intellective soul. For, the Word of God is the Son Himself. Neither did He come in the flesh to replace, but rather to assume and preserve from sin and save the rational and intellective soul of man” (Seventh Anathema).
The Synodical Letter of the First Council of Constantinople likewise condemned this belief:
“The dispensation of the flesh is neither soulless nor mindless nor imperfect; and knowing full well that God’s Word was perfect before the ages, and became perfect man in the last days for our salvation.”