At the Council in Nicea in 325 Constantine proposed the clause, that the Son was “of one substance” (homoousios) with the Father. The decision of the Council became the basis of the Nicene Creed which is a creed used by both the Western and Eastern churches. Although Arius was defeated, the teaching of Arianism did not die.
Later a new Emperor, Theodosius, who did not agree with the Arians, called a Council in Constantinople in 381. The eventual outcome was to describe God as three hypostases (three persons) in one ousia (essence). Tertullian, a theologian from Carthage, had already suggested a Latin version: “three persons and one substance”.
This Council finalised the creed we call the Nicene Creed. Around the same time in the Western church the Apostles’ Creed was beginning to find its final shape (the Eastern church never used it).
Chalcedon
The focus of theological debate then moved from Christ’s relationship with God to the relation of his human and divine natures. Another Council met at Chalcedon, near Constantinople, in 451. This Chalcedon definition has become the standard statement of orthodox belief in the Western church. Most, but not all, of the Eastern church also accepted it.
A Latin Bible
In 382 Bishop Damasus, of Rome, persuaded his secretary Jerome to translate the whole bible into Latin. Jerome edited a new Latin bible which became the bible for the western church for the next 1000 years. It is known as the Vulgate (meaning common).
Dale