Question: "Who was John Cassian? What is Cassianism?"

Answer: John Cassian was a monk who died approximately 430 years after the birth of Christ. His writings are credited with supporting Western Christianity’s development of themes such as the monastic lifestyle and the infamous Seven Deadly Sins. Cassian’s approach to grace, faith, and free will is a point of controversy, with many Reformed scholars accusing him of being semi-Pelagian. Yet Cassian’s views were not the same as Pelagius, nor do his writings entirely mesh with later Pelagian or semi-Pelagian works. For this reason, albeit rarely, his particular theological views are referred to as Cassianism.

Cassian’s time as a monk was instrumental to his writing and his theological views. He was an ascetic, that is, someone who actively rejected worldly pleasures. At the same time, Cassian’s asceticism was tempered by a certain level of common sense and not taken to the extreme of some other monks. His approach to the monastic lifestyle would later become influential in the growth and development of the Benedictine Order.

Theologically, Cassian is the subject of some controversy. He wrote in opposition to Nestorianism and seems to criticize it in ways that are also dismissive of Pelagianism. However, Cassian’s views on free will and grace were not entirely aligned with the later Reformed views. Cassian felt that the will could be conquered—and in fact had to be conquered—in order to obtain grace. For this reason, he is often listed as semi-Pelagian. Other scholars disagree with this label, claiming that his approach—occasionally referred to as Cassianism—is really something different.

John Cassian’s writing also expounded on a list that categorized certain “deadly” sins, similar to writings made by other theologians of the time. Cassian’s work, however, deeply influenced Pope Gregory I, who rearranged and condensed Cassian’s list of eight sins into what we now know as the “Seven Deadly Sins.”

John Cassian represents an example of a historical figure whose influence is felt widely across an entire faith but whose name and history have been mostly forgotten.