The first few hundred years of the church were years of expansion. The crucifixion was between 30-33 and Paul's missionary journeys began around 47 and he was martyred about 67. As the Church spread there was only an informal central structure and communication between Christian groups was slow by today's standards but much better than what most people today probably think. We see in the epistles that there were doctrinal discussions that surrounded the Law of Moses, issues of salvation and the nature of Jesus' role as Messiah.

Notions of the law were discussed at what many to consider to be the first Church Council in Jerusalem as recorded in Acts 15. In the first two chapters of Galatians, Paul tells us of two of his trips to Jerusalem to see the other Apostles and compare what he was preaching to their message. The sense of this portion of the letter is that Paul had functioned largely on his own for the first three years of his ministry (see Galatians 1.18) until he finally did go to Jerusalem. At this council there was no disagreement about the nature of the gospel message but some discussion around the details of the law.

Through much of next 300 years, Christians were often persecuted by both the Jews and the Romans at different times and for different reasons. The Jews were stuck in a legalistic piety that tried to exclude those who did not follow the law of Moses. Paul had preached freedom in Christ. The popularity of Christianity among the masses especially slaves was of concern to the Roman authorities. The educated Greeks tried to make Christianity into a philosophy and by the mid 100's the definition of Christianity was challenged by the Gnostics and people like Marcion who had formed their own churches on the one side and the Judaizers on the other. During this time there were meetings of Bishops that are called the Pre-ecumenical Councils below.

In 313 Emperor Constantine and his co-emperor Licinius officially recognized Christianity in the Edict of Milan, but a Christianity which by many accounts was fragmented. It is said that Constantine wanted to have a more united Christianity for political reasons hence the need for the Ecumenical Councils. It could also be that he was honestly confused by the disputes he saw around him. The Orthodox often refer to these as Imperial Councils as they were convened by the Emperor (the Roman Catholic Church does not agree and cites the reigning pope as the one who convened them.)  It should be noted that Christianity was not the official state religion until 380 with the Edictum de Fide Catholica. This recognition presented problems of its own but that is another discussion. Here we are looking at the the role the Councils play in the Church.

The Christian Churches today have varying notions as to how important some of these councils were. Eastern Orthodox, Oriental Orthodox, Nestorian, Roman Catholic, and Anglican churches are among those who trace their clergy by apostolic succession back to this period and beyond to the earlier period referred to as Early Christianity. Most protestant denominations claim they are recovering this Early Christianity from beneath the load of tradition. Church unity, however, was not maintained through this period even with these councils.

The Church of the East (Nestorian) accepts the first two of the seven councils, but rejects the third, the Council of Ephesus (431), and all the subsequent councils. The Oriental Orthodox accept the first three councils but reject the fourth council (Calcedon) and those following. The Quinisext Council (692), between the Sixth and Seventh, attempted to establish the Pentarchy and is not generally considered one of the first seven ecumenical councils. It is not accepted by the Roman Catholic Church but it is by the Orthodox. The Roman Catholic Church recognizes a total of 21 councils that include the first seven.

The East–West Schism, formally dated to 1054, was still almost three centuries beyond these councils, but already by the time of the second council of Nicaea in 787 the major western sees, although still in communion with the state church of the Byzantine Empire, were all outside the political control of the Empire. In 800 Pope Leo III crowned Charlemagne as emperor beginning what is known as the Holy Roman Empire putting additional political strains on the unity of the Church. The Roman Pope clearly had great political power at this point and was making more claims to being the universal shepherd of the universal church. 

The links in the table below go to more detail on these councils in different groupings. They tell different stories from different perspectives.

Grouping Comment
Pre-ecumenical Councils Councils that date before the Seven below. Many dealing with issues that arose from the persecution of the Church.
The Seven Ecumenical (Imperial) Councils These are the councils that most familiar with Church councils will know. 
The councils and the Creed The story of the Nicene Creed.
The 21 Councils of the Roman Church What Rome has to say about the matter.
The Councils of the Orthodox Largely from Orthodox sites, a catalog of the Church Councils of the Orthodox Church. It gives a perspective on Church History from the Eastern perspective that is not familiar to most of us in the west.
The Councils and the Canon Church councils have weighed in on which books should be in the Bible. This turns out to be a confusing topic and what I have so far in not ready for publication.
Other Synods and Councils Councils that do not fit into the other categories (currently there is some overlap).