People often assume that more unity existed in the early Church than actually did. In truth, the earliest Christians had to struggle to define their faith. Throughout history, Christians have struggled to distinguish between true and false teaching. Even some books in what is now known as the New Testament were the subject of heated debate among early Christians. Together, these believers had to struggle and prayerfully discern which books would be included in the final canon, and which would be kept within the tradition of the Church, but not given authoritative status.

Likewise, many of the central teachings of Christianity became more defined through time. For example, although the doctrine of the Trinity — the belief that there are three divine persons, Father, Son, and Holy Spirit, who exist and work together in unity — is rooted in Scripture, it would not necessarily be plainly apparent from a reading of the Bible.

In this context of division, church councils were often called by the Roman (Byzantine) emperor as a way to unify the churches. This was in the interest of the civil authorities since, as Christianity became more widespread, doctrinal disputes had a marked effect on civic peace. These councils provided a forum for Christians to meet and struggle through the different issues, seeking a prayerful consensus on matters that were critical to the life of faith.

Sometimes the battles about theology were quite fierce. People believed things with all their hearts and fought for them, only to have their views rejected by the Church as a whole. There is an old saying attributed to Tertullian that “the blood of the martyrs is the seed of the Church,” meaning that the teachings of the Church come from the blood, sweat, and tears of the earliest Christians. Long before official councils were called, bishops had been assembling to dispute and define theology for their flocks. One of best-known and earliest examples of this is the Council of Jerusalem, which is spoken about in Chapter 15 of the book of Acts.