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How did the Council of Nicaea respond to Arianism?

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The First Council of Nicaea, convened in 325 CE by the emperor Constantine, responded to the challenge of Arianism by formally condemning the doctrine as a heresy.12

Arianism, proposed by the presbyter Arius, asserted that Jesus was a created being rather than divine, arguing that the Son was of a different order of existence than the Father. To safeguard orthodox belief, the council issued a statement of faith known as the Creed of Nicaea.12

The council’s most significant action was the inclusion of the term homoousios (Greek for "of one substance") to describe the relationship between the Son and the Father. By declaring the Son to be homoousion tō Patri, the council affirmed that Christ is completely divine and shares the same substance as God the Father, thereby rejecting the Arian view that the Son was a lesser, created entity.123