For the first time, the assembled bishops sought to unify all Christian factions and formulate one creed that articulated Christian beliefs. They sought a statement using scriptural language that precisely represented the church's orthodox doctrine and excluded any heresies (particularly the Arian heresies). Subsequent councils would deal with other heresies. They began with the baptismal creed used by Bishop Eusebius of Caesarea, adding clarifications as they worked through it. This newly formulated creed became known as the Nicene Creed.

New language in the creed included phrases such as “God from God, Light from Light, true God from true God; begotten, not made; from the substance of the Father.” Arius and his followers could recite other creeds but could not truthfully recite these precise words. Emperor Constantine followed through with a statement that anyone refusing to sign the creed would be exiled. Arius, Theonas of Marmarica in Libya, and Secundus of Ptolemais refused and were excommunicated and exiled. Arius's works were ordered to be destroyed.

Out of a response to heresies, the young Christian church had together established rules for itself and a creed. Their next challenge was to establish the New Testament canon.