There were three important ecumenical councils in the early centuries after Christ that clarified doctrines related to the Trinity, especially the doctrines of the divinity of Jesus Christ and the divinity of the Holy Spirit.
The Nicene Creed, which was based on what we now call the "Apostles' Creed," affirmed the Trinity and highlighted the divinity of Jesus. This council was called by Constantine because of a controversy between Arius, who considered that Jesus was not fully God, and Athanasius, who defended His deity. The council condemned the views of Arius and adopted the position of Athanasius. The creed states that Jesus is "very God of very God."