Filioque

====Eastern Orthodox theology====
In Eastern Orthodox Christianity theology starts with the Father hypostasis, not the essence of God, since the Father is the God of the Old Testament.{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/one-god-one-father One God, One Father]"}} The Father is the origin of all things and this is the basis and starting point of the Orthodox trinitarian teaching of one God in Father, one God, of the essence of the Father (as the uncreated comes from the Father as this is what the Father is).{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/one-god-one-father One God, One Father]"}} In Eastern Orthodox theology, God's uncreatedness or being or essence in Greek is called ''[[ousia]]''.{{sfn|Papanikolaou|2011}} Jesus Christ is the Son (God Man) of the uncreated Father (God). The Holy Spirit is the Spirit of the uncreated Father (God).{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/the-three-divine-persons The three Divine Persons]"}}

God has existences ([[hypostasis (philosophy)|hypostases]]) of being; this concept is translated as the word "person" in the West.{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/the-three-divine-persons The three Divine Persons]"}} Each hypostasis of God is a specific and unique existence of God.{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/the-three-divine-persons The three Divine Persons]"}} Each has the same essence (coming from the origin, without origin, Father (God) they are uncreated).{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/the-three-divine-persons The three Divine Persons]"}} Each specific quality that constitutes an hypostasis of God, is non-reductionist and not shared.{{sfn|Hopko|n.d.(a)|loc="[http://oca.org/orthodoxy/the-orthodox-faith/doctrine/the-holy-trinity/the-three-divine-persons The three Divine Persons]"}} The issue of ontology or being of the Holy Spirit is also complicated by the ''Filioque'' in that the [[Christology]] and uniqueness of the hypostasis of Jesus Christ would factor into the manifestation of the Holy Spirit. In that Jesus is both God and Man, which fundamentally changes the hypostasis or being of the Holy Spirit, as Christ would be giving to the Holy Spirit an origin or being that was both God the Father (Uncreated) and Man (createdness).

The [[immanence]] of the Trinity that was defined in the finalized Nicene Creed. The economy of God, as God expresses himself in reality (his energies) was not what the Creed addressed directly.{{sfn|McGuckin|2011b|pp=170–171}} The specifics of God's interrelationships of his existences, are not defined within the Nicene Creed.{{sfn|McGuckin|2011b|pp=170–171}} The attempt to use the Creed to explain God's energies by reducing God existences to mere energies (actualities, activities, potentials) could be perceived as the heresy of semi-[[Sabellianism]] by advocates of [[Personalism]], according to Meyendorff.{{sfn|Meyendorff|1996|p=178}}{{sfn|Ware|1993|loc=[http://www.intratext.com/IXT/ENG0804/_P12.HTM God in Trinity]}} Eastern Orthodox theologians have complained about this problem in the Roman Catholic dogmatic teaching of ''[[actus purus]]''.{{sfn|Meyendorff|1986|loc=[http://www.myriobiblos.gr/texts/english/Meyendorff_13.html §3]|ps=: "The Orthodox side ... was gradually transcending a purely defensive stand, by discovering that the real problem of the ''Filioque'' lies not in the formula itself, but in the definition of God as ''actus purus'' as finalized in the ''De ente et essentia'' of Thomas Aquinas, vis-à-vis the more personalistic trinitarian vision inherited by the Byzantines from the Cappadocian Fathers."}}