Consubstantial (Latin: consubstantialis) is an adjective used in Latin Christian christology, coined by Tertullian in Against Hermogenes 44, used to translate the Greek term homoousios. "Consubstantial" describes the relationship among the Divine persons of the Christian Trinity and connotes that God the Father, God the Son, and God the Holy Spirit are "of one being" in that the Son is "generated" ("born" or "begotten") "before all ages" or "eternally" of the Father's own being, from which the Spirit also eternally "proceeds."
History of term 
Since the Latin language lacks a present active participle for the verb "to be," Tertullian and other Latin authors rendered the Greek noun "ousia" (being) as "substantia," and the Greek adjective "homoousios" (of the same being) as "consubstantialis". Unlike the Greek words, which are etymologically related to the Greek verb "to be" and connote one's own personal inherent character, "substantia," connotes matter as much as it connotes being.
The term is also used to describe the common humanity which is shared by all human persons. Thus, Jesus Christ is said to be consubstantial with the Father in his divinity and consubstantial with "us" in his humanity. This term was canonized by the Church in 325 at the Council of Nicaea.
It has also been noted that this Greek term "homoousian" or "consubstantial", which Athanasius of Alexandria favored, and was ratified in the Nicene Council and Creed, was actually a term reported to also be used and favored by the Sabellians in their Christology. And it was a term that many followers of Athanasius were actually uneasy about. The "Semi-Arians", in particular, objected to the word "homoousian". Their objection to this term was that it was considered to be un-Scriptural, suspicious, and "of a Sabellian tendency." This was because Sabellius also considered the Father and the Son to be "one substance." Meaning that, to Sabellius, the Father and Son were "one essential Person." This notion, however, was also rejected at the Council of Nicaea, in favor of the Athanasian formulation and creed, of the Father and Son being distinct yet also co-equal, co-eternal, and con-substantial Persons.
Some English-speaking translators and authors still prefer the words "substance" and "consubstantial" to describe the nature of the Christian God.
For example, in the Church of England the word "consubstantial" is sometimes used to describe the relationship between the sacred elements and the body of Christ. Some note that this is distinct from the Roman Catholic transubstantial relationship of elements and the divine. Unless the reader has knowledge of the history and special ecclesiastic meaning of these terms, their use might make the understanding of the Christian God as transcendent problematic. That is, being above matter rather than consisting of matter.
Translations of the Nicene Creed into English often reflect the preference of using "of the same being" rather than "consubstantial" to describe the relationship of the Son to the Father. When the new translation of the Roman Missal was introduced in 2011, "consubstantial" was introduced as the more accurate translation of the text in Latin. It replaced the phrase "of one being" and was attacked as being archaic. The change was defended because "one in being" was considered to be too ambiguous.
See also 
- Select Treatises of St. Athanasius – In Controversy with the Arians – Freely Translated by John Henry Cardinal Newmann – Longmans, Green, and Co., 1911, footnote, page 124
- New Missal translation called ‘archaic, sexist’, National Post April 11 2011
- "Consubstantial": At the root of our Faith – Why it is in the Creed Diocese of Cleveland