Homoiousios

The term is from the Greek homoi, “similar,” and ousia “being,” meaning “of similar being.” It is associated with the Arian understanding of the relation between the Father and the Son (or Word). Arius understood Father and Son to be of similar-but not identical-being or essence. Although Father and Son were considered to be in some sense similar, they were also considered in some sense dissimilar. Arius regarded the Son or Word to be a created being, as a boat is created by a shipbuilder. For Arius, Father and Son could not be said to be of one substance. The Council of Nicaea in 325 declared such an understanding of the relationship between Father and Son to be inadequate to provide for the divine salvation of the world through the Son. It insisted that Father and Son are not merely similar but are of one substance, one being, homoousios. See Homoousios; see Arianism; see Ecumenical Councils.