At the time of this patriarch, a man by the name of Sabellius appeared in Alexandria who was teaching that the Father, the Son, and the Holy Spirit are one person.
The hagiographer Alban Butler (1710–1773) wrote in his Lives of the Fathers, Martyrs, and Other Principal Saints under August 23, St. Theonas, Bishop of Alexandria, Confessor
HE succeeded St. Maximus in that patriarchal chair in 282, and held it almost nineteen years, being himself, by the shining light of his sanctity and learning, the greatest ornament of that church at a time when it was in both respects most flourishing.
St. Pierius was then priest and catechist in that church, and supported the high reputation of its school, so as to be styled himself the young Origen.
Photius tells us, that in a book which he wrote upon St. Luke's gospel, he proved that the disrespect which is shown to images falls back upon that which they represent.