Nicaea was where the First Ecumenical Council was held in 325 a.d. The council assembled at the order of Emperor Constantine to discuss several dogmatic points, including the Arian heresy. The emperor allowed the bishops to use the imperial post to travel to the city of Nicaea. The council also discussed several disciplinary issues. The Coptic Church was represented by Patriarch Alexander of Alexandria, with his deacon Athanasius (who succeeded him as 20th patriarch of Alexandria).

In this council, Arius was excommunicated and his was condemned. The emperor did not take part in the itself but initiated a tradition of theologian emperors, which developed in later centuries, such as during the reign of in the sixth century and during the time of the iconoclastic crisis. The Bishop of of Cordova was selected as an adviser to the emperor for religious affairs, and hence presided over the council. This council is regarded as the standard of orthodoxy. The Council of Ephesus and the Council of Chalcedon issued canons stating that no Creed would be accepted except the Creed defined in the Councils of Nicaea and Constantinople. The Bishop of Rome (that is, the pope) was too old to attend this council and so sent two delegates to represent him. This lack of attendance by the Pope of Rome became standard in councils to follow, until the Council of Vatican II.

The of the Coptic canonical works has not survived, with the exception of only one Coptic that contains the canons of the councils and synods from Nicaea, Ancyra, Laodicia, Constantinople, and so on. This manuscript is scattered throughout the libraries of the Vatican, Naples, Paris, Michigan, and the French Institute in Cairo. Starting in the 12th century, the Copts used the Arabic versions of this canonical corpus. See also NICENE CREED.