Pope Alexander I of Alexandria

Alexander I of Alexandria inherited a Church riddled with internal fractures: disputes over when to celebrate Easter, the rogue actions of Meletius of Lycopolis, and most critically, the rise of Arianism - a theological position that threatened the orthodoxy he defended. As patriarch, he became the chief opponent of Arius's teaching at the First Council of Nicaea, where the stakes were nothing less than how Christianity would define the divine. He also mentored Athanasius of Alexandria, who would carry forward the fight and become one of the Church Fathers. The Coptic Orthodox Church regards him as Pope; the Catholic Church does not.