Following the Apostolic Age, from the 2nd century onwards, a number of controversies developed about how the human and divine are related within the person of Jesus. As of the 2nd century, a number of different and opposing approaches developed among various groups. For example, Arianism did not endorse divinity, Ebionism argued Jesus was an ordinary mortal, while Gnosticism held docetic views which argued Christ was a spiritual being who only appeared to have a physical body. The resulting tensions led to schisms within the church in the second and third centuries, and ecumenical councils were convened in the fourth and fifth centuries to deal with the issues. Eventually, by the Ecumenical Council of Chalcedon in 451, the Hypostatic union was decreed—the proposition that Christ has one human nature and one divine nature united with neither confusion nor division—making this part of the creed of orthodox Christianity. Although some of the debates may seem to various modern students to be over a theological iota, they took place in controversial political circumstances, reflecting the relations of temporal powers and divine authority, and certainly resulted in schisms, among others that which separated the Church of the East from the Church of the Roman Empire.

So as I mentioned, in 325, the First Council of Nicaea defined the persons of the Godhead and their relationship with one another, decisions which were ratified at the First Council of Constantinople in 381. The language used was that the one God exists in three persons (Father, Son, and Holy Spirit); in particular, it was affirmed that the Son was homoousios (of the same being) as the Father. The Nicene Creed declared the full divinity and full humanity of Jesus.