 The view that the Son was 'of the substance of the Father, God of God...very God of very God' was formally ratified at the First Council of Nicaea in 325 AD.The Holy Spirit was included at the First Council of Constantinople (381 AD), where the relationship between the Father, Son and Holy Spirit as one substance ("ousia") and three co-equal persons ("hypostaseis") was formally ratified.Some Trinitarians say the doctrine of the Trinity was revealed in New Testament times; others, that it was revealed in the Patristic period.