Introduction John Cassian was a zealous monk whose theology (unfortunately, one might say) has been massively influential on the church’s understanding of the whole of the gospel since the fifth century. His particular theology (commonly known as semi-Pelagianism), which was developed largely in response to Augustine’s doctrines of predestination, grace, and free will, has been adopted by many Christians—academics, clergy and lay people alike—throughout the centuries.Two major influences were at work in Cassian’s life and teachings. First, Greek neo-platonic philosophical theology shaped his understanding of anthropology in a way that prevented him from being able to engage Augustine on the...