How the early church worked to preserve unity
During the early centuries, Christians from both areas (European and Middle Eastern) took part in councils at which they agreed on the clearest ways to describe the nature of God as three-in-one and the way in which Christ was both God and Man.
In the 300’s they met to counter-act a teacher named Arius who denied the biblical teaching that Christ is God. In response the churches produced the “Nicene Creed” (named after a city in Turkey called Nicea) which used clear terminology to affirm that Father, Son, and Holy Spirit are equally God. The barbarian tribes were followers of Arius, but during the following centuries these tribes one by one accepted the Nicene Creed.
The next issue, continuing into the 400’s, was about Christ being fully God and fully human. For example, a man named Nestorius agreed that Christ was human, but not fully God. His followers, the Nestorians, brought the teachings of Jesus to China starting in 635. A man named Eutyches taught that Christ had only a God-nature, not a human nature. In response, the churches produced a statement in 481 that upheld the biblical position that Christ is true God and true man.
Those who opposed this statement moved to the east, beyond the control of the Roman empire. Here are some examples. The Nestorian church moved to Persia and later brought Christianity to China. The followers of Eutyches are called “monophysites” (one-nature), and still continue in the Christians of Egypt, who are now called the “Copts.” Some of these churches are also called “Oriental Orthodox Churches ” because they are located to the east of the Roman Empire) or “non-Chalcedonian” churches (because the agreement they rejected was made at a city called Chalcedon).
For details on these non-Chalcedonian churches, see the book Lost Christianities by Philip Jenkins. For a chapter-long summary, see chapter 6 of the book A Global History of Christians, by Paul Spickard and Kevin Cragg (Grand Rapids: Baker, 1994).
More about the Councils
Altogether there were seven gatherings of eastern and western church leaders. They are called the “ecumenical councils.” (The word “ecumenical” means they were gatherings of the entire community). Here is a summary:
The Seven Ecumenical Councils:
| Year | City | Highlights |
| 325 | Nicea (in Turkey) | God the Son is the same substance as God the Father |
| 381 | Constantinople (in Turkey) | Re-affirmed 325, re-affirmed the Holy Spirit as also of the same substance, summed up in the Nicene Creed |
| 431 | Ephesus (in Turkey) | Re-affirmed Nicene Creed and condemned Nestorius |
| 451 | Chalcedon (in Turkey) | Produced a statement “the definition of Chalcedon” that was contrary to both Nestorius and Eutyches |
| 553 | Constantinople | Again condemned Nestorius |
| 680 | Constantinople | Affirmed that Christ has both a divine will and a human will |
| 787 | Nicea | Approved use of religious images |
In addition to the ecumenical councils, both the eastern and western churches continued to have their own meetings.
Here are a few samples:
| Year | Location | Highlights |
| 589 | Synod of Toledo (in Spain) | added the words “and the son” to the Nicene Creed. |
| 662 | Synod of Whitby (in England) | brought the Christian movement from Ireland (the Celtic church) into harmony with the practices of the Catholic church. |
| 1215 | Lateran Council 4 (in Rome) | decreed that the Catholic priest changes the bread and wine of communion into the body and blood of Christ (transubstantiation). |
| 1870 | Vatican Council 1 (in Rome) | Declared that the pope cannot make a false teaching when he is teaching officially (infallibility) |
| 1962-3 | Vatican Council 2 (in Rome) | Allowed Roman Catholics to take wine as well as bread, and to hold church services in their own language (not just Latin). |