(Nicaea I) was convoked in 325 in Nicaea (Bythani) by the emperor Constantine the Great and chiefly concerned the teaching of Arius. 318 bishops, notably St. Nicholas, bishop of Myra, Spyridon, bishop of Trimyphunteia, were present. The council condemned the Arian teaching that repudiated the divine nature of Jesus Christ and his equality with God Father. It also approved of the Creed where upon the emperor Constantine’s suggestion the term “of the same substance” was introduced. Finally the council promulgated twenty church laws called canons as well as separated the Easter from the Jewish Passover and fixed it on the first Sunday following the vernal equinox. Feast day: 29 May (11 June).
The emperor Constantine is depicted twice: as greeting the Council participants and chairing the Council.