At which councils was the doctrine of the Trinity formalized?

• A. Councils of Nicaea and Constantinople.
• B. Council of Jerusalem.
• C. Council of Trent.
• D. Council of Ephesus.

Answer: (A)

The main idea tested is how the church crystallized the Trinity through key ecumenical councils in the fourth century. At Nicaea, the church rejected the view that the Son was a created being and declared that the Son is of one substance with the Father. This affirms the Son’s full divinity within the Godhead and rejects any division between the Father and the Son. Then, at Constantinople, the creed was expanded to affirm the Holy Spirit’s divinity and to clarify that the Spirit, like the Father and the Son, is fully God and worthy of worship, proceeding from the Father. This completes the pattern of one God in three persons who are co-eternal and co-equal. Other councils addressed different issues in church life and doctrine, but the formal articulation of the Trinity as Father, Son, and Holy Spirit in one substance comes from these two councils.