Shortly after the turn of the second century, Pliny the Younger, governor of Bithynia in Asia Minor, consulted Emperor Trajan about the rapidly spreading Christian "superstition" in his district, asking him what he should do about it. By interrogating a few people, Pliny learned that "on an appointed day," Christians habitually met before daybreak and recited "a hymn to Christ, as to a god."

These hymns, which go back to the earliest days of Christianity, sharply contradict the popular notion that the doctrine of the Incarnation is only a brainchild of fourth-century theologians playing irrelevant word-games. Long before Christian emperors convened their solemn assemblies, thousands of Christian worship services sang the praises of the Holy Child of Bethlehem.

This is one reason the orthodox party eventually triumphed in the Arian controversy: Athanasius simply argued theologically what the church had been singing for two centuries. But if the Arian controversy settled the issue of Christ's full divinity and humanity, it did not settle the issue of exactly how the divine Christ became human. That concern was left to later theologians.

Christ without a Human Soul

With the conversion of Emperor Constantine to Christianity (A.D. 312), the church marked a new phase in its triumphant expansion. Almost overnight it became fashionable to believe. As a result, churches were crowded, as professor Alan Richardson said, "with the half-converted, the socially ambitious, and the ill-instructed." The Greek idea of God as utterly transcendent reappeared with new vigor among professing Christians—with mixed results.

During the fourth century, two schools of theology offered contrasting interpretations of biblical passages speaking of the Incarnation. One of these was at Alexandria, the other at Antioch. The Alexandrians emphasized strongly the divine nature; the Antiochenes, the human. One began in heaven and moved to earth; the other commenced on earth and looked to heaven.

The first sophisticated explanation of the Incarnation came from the Alexandrian side of the debate, from one Apollinarius (c.310-c.392), an elderly pastor of Laodicea who greatly admired Athanasius, leader of the Alexandrian school. We may be inclined to think of all heretics as dark, sinister figures bent on the overthrow of Christian truth, but Apollinarius's lapse into heresy didn't happen until he was over 60. Till then he enjoyed a reputation as a pillar of orthodoxy. Churches throughout the empire experienced only shock when they first heard that the venerable bishop had fallen into error.

Echoing Athanasius, Apollinarius began his case for the Incarnation with the full deity of Christ: only God could save the world, and, if Christ is Savior, he must be divine. But the question is, how?

The old scholar struck upon the idea of approaching the question from a psychological view. He felt that human nature embraced the body and the soul. But at the Incarnation, the divine Word displaced the animating and rational soul in a human body, creating a "unity of nature" between the Word and his body. Humanity, he felt, was the sphere, not the instrument of salvation—merely the place where salvation occurred, not a means of salvation. Christ, therefore, had only one nature: Apollinarius spoke of "one enfleshed nature of the divine Word." The Alexandrian stress on Christ's deity remains, but the only thing human about Christ was his physical body.

Apollinarius, definite as his heresy was, deserves our praise for a pioneering effort that forced the church to think more deeply about Christ. His fault lies in his inability to push any further into the heart of truth. The widespread respect that Apollinarius had gained over the years explains why he was never exiled—though, as a heretic, he was forbidden to worship in the Catholic church. He died in his eighties, remaining a scholar and writer to the end.

Objections to Apollinarianism arose quickly. Does the Gospels' picture of Jesus not depict a normal human psychology, showing Christ with a human mind and human emotions? And if the Word displaced the rational human soul, with its powers of choice and sin, how could Christ be fully human, and therefore, how could human beings be fully redeemed? If the Word did not unite full humanity with himself, then how can we hope to be saved?

In this atmosphere, the Council of Constantinople (381) effectively silenced the Apollinarian teaching. It simply was not an adequate description of the Incarnation.

Mother of God?

The second "heresy" was associated with the name Nestorius, a famous preacher at Antioch, who in 428 was appointed archbishop of Constantinople. In the shadow of the imperial palace, Nestorius proved to be a devout, well-meaning monk but a strident, tactless preacher. On the streets, his persecuting temper earned him a nickname, "Firebrand." Shortly after assuming his duties in the capital, he launched a sermonic attack against the popular term Theotokos, or "God-bearer," as a title for the Virgin Mary. Ordinary church folk assumed that their new preacher regarded the Savior as an inspired man, nothing more.

In point of fact, Nestorius meant nothing of the sort. He thought the term might suggest that the babe born of Mary was not human but God only, which he felt was another form of the Apollinarian heresy. He suggested as an alternative the title Christotokos, "Mother of Christ." But his unguarded rhetoric made some think he believed Christ not only had two natures but also two wills, that there were two Christs so to speak, one divine, one human, existing in the one body. Since this appeared to deny the Gospels' portrait of Jesus as an integrated individual, controversy filled the air; charges sounded from pulpits. Cyril, archbishop of Alexandria, called on Nestorius to recant.

To settle the uproar, the emperor adopted the time-honored policy of summoning a general council. It met at Ephesus in the summer of 431. Nestorius refused to attend, but the emperor, who had once supported Nestorius, acceded to Cyril's demands and deposed the firebrand. Repudiated, Nestorius found himself exiled to his former monastery at Antioch even as a new bishop assumed his pulpit in Constantinople. Nestorius's followers were also expelled from the church and soon established the Nestorian Syrian churches of the Middle and Far East, some of which survive to this day.

Nestorius lived until late in 451, long enough to welcome Pope Leo's doctrinal epistle (or "Tome") and the "definition" of orthodoxy announced at the Council of Chalcedon. He received the council's conclusions as his own. "I have endured the torment of my life," he said just before dying on the borders of the empire. "Every day I beseech God to accomplish my dissolution, whose eyes have seen the salvation of God."

Fine words from a maligned man. But the Nestorian controversy did serve one lofty purpose. The more extreme members of the Antioch school made clear the need to talk about Christ's deity and humanity in convincing terms, especially terms describing the union of both in a single person.

"Robber Council"

Soon after the Council of Ephesus, a third disgraceful affair called Eutychianism spread controversy throughout the East. From a monastery near Constantinople, an elderly but unlearned monk named Eutyches (c.378–454) began to defend Christ's deity, a teaching sometimes called monophysitism (from the Greek, meaning "one nature"). He taught that Christ's humanity was swallowed up in his deity, just "as a drop of honey that falls into the sea dissolves in it." It was virtually a rerun of Apollinarianism, and before that, docetism (the teaching that Christ only seemed to be a man).

Patriarch Flavian of Constantinople pronounced the monk a heretic. In Alexandria, however, Dioscorus, the city's patriarch, was eager to assert his power in Constantinople. At his request, the emperor once again summoned an "imperial council." This one at Ephesus (449) allowed Dioscorus to rehabilitate Eutyches, but the rest of the church saw through the politics. Pope Leo dismissed it as a "robber council" and joined Emperor Flavian in asking the emperor for a new council. Such was the shady background of the historic Council of Chalcedon, a town not far from Constantinople.

In 451 nearly 400 bishops quickly indicted Dioscorus for his actions at the "robber council" and then set forth the definition that has become classical orthodoxy. Chalcedon admirably states what Christ is not.

Against the earlier heretic Arius, the assembly affirmed that Jesus was truly God, and against Apollinarius that he was truly man. Against Eutyches it confessed that Jesus' deity and humanity were not changed into something else, and against the Nestorians that Jesus was not divided but was one person.

In order to deny the Greek conception of God as remote and uninterested, but at the same time to be loyal to Scripture, Chalcedon offers no "explanation" of Jesus' mystery. The council fathers knew that Jesus fits no class. He is absolutely unique. Chalcedon left the mystery intact; the church remained a worshiping community.

But the affirmation also made it possible to tell the story of Jesus as good news. Since Jesus was a normal human being, he could fulfill every demand of God's righteous law, and he could suffer and die a real death. Since he was truly God, his death was capable of satisfying divine justice. God himself had, by his grace, provided the sacrifice.

Bruce L. Shelley is senior professor of church history at Denver Seminary and author of Church History in Plain Language (Word).