ARIANISM, a theological system in the early
Christian Church, named after Arius, a presbyter
at Alexandria. In opposition to his bishop
Alexander, Arius asserted that there was a time
when the Son was not coequal, since the Father
who begot must be before the Son who was
begotten, and the latter therefore could not be
eternal. As many prominent bishops sided with
Arius, synods were called on both sides, and
the most acute intellects of the church discussed
the question. The general council of Nice (325), attended by 300 bishops, condemned Arius and declared the Son to be consubstantial with the Father; but Arius nevertheless gained the favor of Constantine and won many new adherents. After his death (336) the movement spread more rapidly than before. When Constantine died in 337, the empire was divided among his three sons, two of whom, Constantine and Constans in the West, accepted the Nicene creed, while Constantius in the East was a decided favorer of Arianism. An anti-Nicene council at Antioch (341), consisting of 90 bishops, issued decrees on the ground of which Athanasius, who in 338 had returned from exile to his diocese, was again deposed. In the West, on the contrary, a synod at Rome in 343 declared Athanasius innocent of the charges preferred against him and the authors of his exile heretics. In order to put an end to this conflict, Constantius and Constans (Constantine had died in 340) convoked the general synod of Sardica in Lower Mœsia in 343 or 344 (not, as has heretofore been generally assumed, in 347). The Arians, having a minority of the 176 bishops present, held a council of their own, at first in the imperial palace in Sardica, and subsequently at Philippopolis. Each party anathematized the other; but the Nicæans triumphed. Constantius so far yielded to the remonstrances of Constans as to allow the return of Athanasius (349); but when he became soon after sole ruler of the empire, his influence at the synods of Arles (353) and Milan (355) secured the condemnation of Athanasius and the adoption of Arian decrees. Pope Liberius and several bishops, among them Athanasius, were banished, and Arianism was completely successful. The sect now became divided into