The document discusses the Council of Nicea, which was held in 325 AD to address disputes about the relationship between God the Father and God the Son. The Council condemned Arius' views, produced the Nicene Creed affirming Jesus as fully God and fully man, and helped bring unity to the church. Later ecumenical councils such as Chalcedon reaffirmed the Nicene Creed and further clarified the dual nature of Christ. The councils defended orthodox views of the Trinity and nature of Christ against heresies such as Arianism, Apollinarianism, Nestorianism, and Eutycheanism.