consubstantial

Consubstantial is a theological term used to express that two or more entities share the same single substance or essence. In Christian theology, it most often refers to the relationship between the Son and the Father: the Son is consubstantial with the Father, i.e., of the same divine nature.

Etymology: From Latin con-substantialis, from substantia substance; used in Latin translations of the Nicene Creed. The corresponding Greek term is homoousios, which is often translated into English as “of the same substance” or “of one Being.”

Historical context: The term arose in the context of the Arian controversy and was formally affirmed at the First Council of Nicaea (325) as “of the same substance as the Father” to affirm the full divinity of the Son. The later Creed (Constantinopolitan, 381) continued this language in most Western translations. In some traditions, “consubstantial” is the standard English rendering of the Latin version of the creed, while others use “one in Being” or “of one hypostasis.”

Theological significance: It supports the doctrine of the Trinity, preserving unity of essence while distinguishing persons; it has implications for Christology and soteriology, asserting the Son’s full divinity as coequal with the Father.

Usage today: The term remains common in Catholic, Orthodox, and some Protestant liturgies and doctrinal statements, though it can appear archaic; in ecumenical dialogue, translators may choose variants like “of one being” to reflect Greek terms.