It was the first Christological heresy to seriously threaten the Church. It denied the Divinity of Christ. Arius, while at the Catechetical School in Alexandria in the year 319 C.E., proposed a problem: If the Son of God is begotten of God the Father, then the Father existed before the Son. Since the Father existed before the Son, the Son is unlike the Father. The Son is not co-eternal with the Father. According to Arius, the Son was created by the Father and not Divine as the Father. Arius’ main error was that he imposed time on the eternal (timeless) nature of God. As a father begets a son, he gives his nature to his son. For humans, the father exists before the son, since humans live in time. Begetting for humans is an act embedded in time and matter. This is part of human nature. But for God, the Father gives His spiritual, divine, timeless nature to His only-begotten Son (Heb. 1), so “before” and “after” are meaningless. Even though the Son is begotten of the Father, this does not imply that the Father existed before the Son. Also the Son of God is begotten and not created. (Even a human father only begets his children and does not create them.) Unfortunately Arius failed to understand this fundamental point and thus refused to accept the Divinity of Christ. Arius took his debate from the academic circles to the streets. He quickly gained a large following. After being excommunicated in Alexandria, he fled to Caesarea where Bishop Eusebius helped him spread his errors. In 325, the Council of Nicaea was called to deal with the Arian crisis. The Council excommunicated Arius and declared that the Son is “of the same substance” (homoousion) as the Father. This became part of the Nicene Creed. But the Arians continued to gain power and political influence. They remained a serious threat to the Church for another half century. St. Athanasius was the great defender of the Faith against this heresy.