In Christian usage, the Greek word hypostasis, the range of whose meanings is illustrated in Liddel and Scott's Greek Lexicon, has a complicated and sometimes confusing history. Its basic meaning is "that which stands beneath". It was used by, for instance, Aristotle and the Neoplatonists, to speak of the objective reality (as opposed to outer form or illusion) of a thing, its inner reality. This is the sense in which the term is used in the doctrine of metousiosis. In the Christian Scriptures this seems roughly its meaning at Hebrews 1:3. Allied to this was its use for "basis" or "foundation" and hence also "confidence," e.g., in Hebrews 3:14 and 11:1 and 2 Corinthians 9:4 and 11:17.

In early Christian writers it is used to denote "being" or "substantive reality" and is not always distinguished in meaning from ousia (essence); it was used in this way by Tatian and Origen, and also in the anathemas appended to the Nicene Creed of 325. See also: Hypostatic union, where

It was mainly under the influence of the Cappadocian Fathers that the terminology was clarified and standardized, so that the formula "Three Hypostases in one Ousia" came to be everywhere accepted as an epitome of the orthodox doctrine of the Holy Trinity. This consensus, however, was not achieved without some confusion at first in the minds of Western theologians, who had translated hypo-stasis as "sub-stantia" (substance, and see also Consubstantial) and understood the Eastern Christians, when speaking of three "Hypostases" in the Godhead, to mean three "Substances," i.e. they suspected them of Tritheism. But, from the middle of the fourth century onwards the word came to be contrasted with ousia and used to mean "individual reality," especially in the Trinitarian and Christological contexts. With regard to the doctrine of the Trinity, hypostasis is usually understood with a meaning akin to the Greek word prosopon, which

As proposed evidence that the idea of multiple hypostases is borrowed from pagan sources, anti-trinitarians often cite a book On the Holy Church, whose author is referred to as Pseudo-Anthimus, because its traditional attribution is thought to be false. Scholars now attribute the book to Marcellus of Ancyra, a strongly anti-Arian and anti-Origenist bishop who was accused of being an apologist for a modalistic conception of God. The book contains the following declaration:

Now with the heresy of the Ariomaniacs, which has corrupted the Church of God..These then teach three hypostases, just as Valentinus the heresiarch first invented in the book entitled by him On the Three Natures. For he was the first to invent three hypostases and three persons of the Father, Son and Holy Spirit, and he is discovered to have filched this from Hermes, Plato and Aristotle. (Source: AHB Logan: Marcellus of Ancyra (Pseudo-Anthimus), On the Holy Church: Text, Translation and Commentary. Verses 8-9. Journal of Theological Studies, NS, Volume 51, Pt. 1, April 2000, p.95 ).

Trinitarians defend their view of multiple hypostases in the single God by, among other things, appealing to Jewish pneumatology (the "Spirit of God" and "Spirit of the Lord"), and angelology (the "Angel of the Lord"); a study of Jewish conceptions of the prophetic "word of the Lord" which comes to the prophets, and by the authority of which they declared "thus says the Lord"; the New Testament's doctrine of the identity of Christ which developed after the resurrection, and the pattern of prayer, devotion, and theological apologetics exhibited in the early Church. Trinitarians acknowledge the debt to pagan philosophy for the terminology and rhetoric of Trinitarianism; and they acknowledge that controversies in the Church have arisen on account of a transference of meaning through any term predicated of God, like hypostasis, which is used by analogy to its proper meaning in philosophical paganism; but they deny that what the terminology is intended to express originates in paganism. Ипостась