It is a commonplace nowadays to consider the nature of Jesus Christ as both God and human. During Jesus' time on Earth, it is believed, he participated fully in the characteristics of both. In the western world, Christians now take this formulation for granted. But this was not always so. In the earliest church, little agreement existed on this question, when it was even considered. The debate focused on two major points, which were discussed during four "world-wide" church councils held over the course of 130 years.

In first three centuries, the Christian church had little time to discuss and regularize important theological points. It was too busy with missionary activity and with avoiding persecution. It was only when Emperor Constantine ended the persecution and provided the church with moral and financial support that Christianity was able to take steps to organize itself. This began with the Council of Nicaea in 325 A.D.

At Nicaea, the debate focused on whether Jesus was human or divine. Arius, a popular and learned preacher from Alexandria, argued that Jesus was human, that he was the first of God's creations. Jesus was not God, then, even though he participated with God in creation.

Arius' opponents argued that if Jesus is only human, then his death and resurrection could not provide the power necessary to save humankind from their sin. After all, Lazarus died and came back to life. This was good for Lazarus, but had no affect on anyone else. Jesus had to be divine in order for him to provide salvation to humanity. The opponents carried the day and their formulation still appears in the Nicaean Creed, Jesus is "true God of true God, begotten, not made."

During the third church council, held at Ephesus in 431 A.D., the debate over Jesus' nature took a different form. If Jesus is human and divine, then how are those two natures mixed together? The Christians from Antioch in Syria held that Jesus' body contained divine and human natures, but that these remained separate. For example, Jesus as God performed miracles, but Jesus as human suffered and died. The problem with this formulation, is that if only Jesus' human nature that dies, then from where does the power of salvation for all humanity come?

The Christians from Alexandria, Egypt, argued the opposite point. Jesus' two natures blended together, although this was not a blend of equal measures. Since divine power far surpasses that of humans, Jesus' human nature was overshadowed and subsumed by his godhood. As a result, Jesus was essentially seen as God and his human character was little more than appearance. This result causes a different problem with salvation. If Jesus as God only appears to die and rise again, then the salvific act never actually took place.

This debate was not resolved until the Fourth Church Council held in Chalcedon 20 years later, when the bishops adopted a middle position. Jesus was both human and divine, and both natures were mixed together equally in the body of that one individual. Thus Jesus at all times acted as both human and divine. As a human being, he was fallible; he was prey to sin and open to temptation, like all other humans. But his divine nature enabled him to remain sinless and to overcome temptation. Similarly, his human character enabled him to die and rise again, while his divine nature enabled the transformation of that achievement into the power of salvation available to all humanity.

It is this formulation that underlies the theology of Christ's nature in Catholicism, Protestantism, and Eastern Orthodoxy. All Christian churches did not adopt it, however. The Churches of Egypt and Syria, who represented the two poles of the debate, did not join the compromise, a position echoed by the churches of Ethiopia and Armenia.