Trinitarianism in the Church Fathers

Debate exists as to whether the earliest Church Fathers in Christian history believed in the doctrine of the Trinity – the Christian doctrine that God the Father, the Son (Jesus Christ) and the Holy Spirit are three distinct persons sharing one homoousion (essence).

Some of the evidence used to support an early belief in the Trinity are triadic statements (referring to the Father, Son and Holy Spirit) from the New Testament and the Church Fathers. 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.^[1]