He is famous for being in the middle of theological controversies over the nature of Christ that racked the Church in the 4th century. He was born into a Jewish family in Palestine. He later moved to Egypt to study and stay with a group of hermits. He then returned to Palestine, founded a monastery and stayed there for thirty years.

He was noted for being an outspoken champion of orthodoxy. He castigated opponents of the faith with little attempt to understand, let alone sympathise with their position. He was involved with debates over the date of Easter and the relationship between the three persons of the Trinity.