Arianism

Arianism, 4th-century Christian heresy founded in Alexandria by the priest Arius. He taught that Christ was not coequal and coeternal with God the Father, for the Father had created him. To curb Arianism, the Emperor Constantine called the first Council of Nicaea (A.D. 325), and the first Nicene Creed declared that God the Father and Christ the Son were of the same substance.

See also: Nicene Councils.