In the fourth century, the Council of Nicea settled the question of the Lord’s deity, and consequently became the touchstone that enables us to address various Trinitarian heresies. A Trinitarian heresy has to do with the unity of the Godhead, and the tri-personal nature of God’s existence, and all without reference to the creation. What is God like in Himself? In the fifth century, the Council of Chalcedon addressed the relationship of the human and divine in Jesus of Nazareth, a question that arose as a result of the Incarnation. Errors on this question are usually called Christological heresies.