Is consubstantiality and homoousis the same thing? Or are they different concepts?

2 Answers 2


They should be taken as meaning the same thing, but the Greek meaning was somewhat complicated when put into Latin, which was further complicated when that Latin was later put into English.

The original Greek word 'ousia' meant essence or substance. The usual Latin for that is 'substantia', meaning essence or substance.

The Greek word 'hypostasis' meant person, or a second meaning was substance. The usual Latin is 'persona', meaning person, or a second meaning is of an actor, or role.

The Greek word 'prosopon' meant face or mask, with a second meaning of person. The usual Latin for that is 'persona', and that is where we get our understanding of 'person' from, but our English ideas suffer from having come from Latin which, in turn, originally came from Greek.

If we went back to the original Greek of the New Testament era, we would see that essence or substance was the meaning, and it is that language that gives the understanding of the Trinity doctrine. Most English speaking people today only think of it as an individual person.

The Greeks described the Trinity as 'mia ousia en trisin hypostasesi' = one substance (essence) in three subsistences [persons]." Unfortunately, that could be misunderstood as saying, "one essence in three substances", which would be 3 gods. When the Latins then said, 'una substantia in tribus personis' = one substance in three persons", they could be misunderstood as saying one 'hypostasis' (person) in three roles. That was the error of Sabellian modalism.

We are 16 centuries removed from this. Yet orthodoxly Christian teaching back then remains the same as today - "Three - Father, Son and Holy Spirit - are God, yet God is not three, but One." That is why I said that English translation from Latin loses something in the translation. And Latin translation from Greek lost something as well. There's nothing like sticking to the original language that such statements were written in, but few of us are linguists, and it was never going to be easy, getting a verbal handle on the awesomeness of Deity.

Conclusion: In order to grasp the concept of consubstantiality, the Greek language needs to be examined, after taking a spiritual sorbet to cleanse our spiritual palate from modern English language 'contamination'.

[This is extracted from Heresies and Orthodoxy in the History of the Church, Harold O.J. Brown pp 63, 128-130 (Hendrickson 1998)]


"Consubstantial" is an English translation of homoousios so yes they are meant to convey the same meaning, namely having the same substance. However, underlying this fact there is a problem: the Greek "ousia" can be understood as something quite different from the English "substance." Merriam Webster provides two definition of the term "ousia":


The issue gets even stickier when the Greek trinitarian formula -- which speaks of three hypostases in one ousia -- translates into "three persons in one being." As Merriam-Webster implies, hypostasis is much closer to ousia than person is to substance. Besides this, there is also the problem that in modern usage, "substance" tends to be understood as something material more than something essential. So while "Consubstantial" and homoousios are intended to be used interchangeably, in practice the terms need to be unpacked.

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