Arsenios Autoreianos was a 13th-century Eastern Orthodox prelate who served as the Ecumenical Patriarch of Constantinople. Born in Constantinople around 1200, he received his education at a monastery in Nicaea and spent time living as a solitary ascetic. He rose to prominence when he was appointed Patriarch of Nicaea in 1255, eventually acting as a co-regent for the young emperor John IV Laskaris. His leadership was defined by his firm commitment to ecclesiastical discipline and his resistance to imperial interference in church matters.
Ecclesiastical career
After his appointment in 1255, Arsenios participated in the double coronation of August 1258. He became a staunch defender of the rights of the young emperor, which led to a direct confrontation with Emperor Michael VIII Palaiologos. Following his refusal to yield to imperial pressure, the emperor had him deposed by a synod in 1265. He died in exile on Marmara Island in 1273.
Legacy and schism
His opposition to the emperor triggered the Arsenian schism, a period of division within the church that endured until 1315. Beyond his political and religious struggles, he is also recognized for his scholarly work, having authored the Synopsis Canonum. He is venerated as a saint within the Eastern Orthodox tradition.