The Arian anathema. Numerous Eastern bishops joined Constantine, seated in the foreground, left of center, in 325 C.E. at the ecumenical Council of Nicaea, illustrated by the Italian painter Cesare Nebbia (1534–1614) for the walls of the Vatican Library’s Sistine Hall. The first council of Eastern bishops, with Hosius of Cordova presiding, at center, formally rejected the Arian understanding of Jesus, declaring it anathema. In this painting, Arius, right of center, appears disgruntled, while a deacon, standing above him at the pulpit, reads aloud the Nicene Creed.
But the council only stirred up the debate for the next 50 years by using the innovative, but vague, term, “homoousios,” meaning “of the same substance,” to define the relation between God the Father and Son. The Roman emperor Theodosius I again attempted to crush Arianism by calling the second ecumenical council, held in Constantinople in 381. The emperor was unsuccessful, and Arianism continued to flourish until the sixth century.