The Nicene Creed (ˈnaɪsiːn; Sýmvolon tis Nikéas) is the defining statement of belief of Nicene or mainstream Christianity and in those Christian denominations that adhere to it. The original Nicene Creed was first adopted at the First Council of Nicaea in 325. In 381, it was amended at the First Council of Constantinople. The amended form is also referred to as the Nicene Creed, or the Niceno-Constantinopolitan Creed for disambiguation.
The Nicene Creed is part of the profession of faith required of those undertaking important functions within the Orthodox and Catholic Churches. Nicene Christianity regards Jesus as divine and "begotten of the Father". Various non-Nicene doctrines, beliefs, and creeds have been formed since the fourth century, all of which are considered heresies by adherents of Nicene Christianity.
In Western Christianity, the Nicene Creed is in use alongside the less widespread Apostles' Creed. In musical settings, particularly when sung in Latin, this creed is usually referred to by its first word, Credo. On Sundays and solemnities, one of these two creeds is recited in the Roman Rite Mass after the homily. In the Byzantine Rite, the Nicene Creed is sung or recited at the Divine Liturgy, immediately preceding the Anaphora (eucharistic prayer), and is also recited daily at compline.
The purpose of a creed is to provide a doctrinal statement of correct belief among Christians. The creeds of Christianity have been drawn up at times of conflict about doctrine: acceptance or rejection of a creed served to distinguish believers and heretics. For that reason, a creed was called in Greek a symbolon, which originally meant half of a broken object which, when fitted to the other half, verified the bearer's identity. The Greek word passed through Latin symbolum into English "symbol", which only later took on the meaning of an outward sign of something.)
The Nicene Creed was adopted to resolve the Arian controversy, whose leader, Arius, a clergyman of Alexandria, "objected to Alexander's (the bishop of the time) apparent carelessness in blurring the distinction of nature between the Father and the Son by his emphasis on eternal generation".