Why did Constantine I call the First Council of Nicaea in 325?

Emperor Constantine I convened the First Council of Nicaea in 325 CE primarily to resolve the theological controversy surrounding Arianism, a doctrine that asserted Christ was a created being rather than divine.12

Constantine’s motivation was rooted in his belief that a divided church would offend the Christian God, potentially inviting divine vengeance upon the Roman Empire and himself. He viewed religious schism as a threat to the stability of the state and considered it his imperial duty to propagate the true religion and remove error.3

Although Constantine initially dismissed the dispute as a trivial matter of academic contention, he hoped that a general council of the church would settle the debate over the nature of the Trinity and restore unity. Despite his efforts, the council's attempt to define orthodoxy through the Nicene Creed did not immediately end the conflict, as Arianism persisted for decades.23