The article describes the history of the British monk Pelagius and his teachings in the early fifth century. Pelagius disputed Augustine’s notion of original sin. Pelagius was a learned man who defended Catholic beliefs. The author reviews a number of Pelagius’s disciples. He follows with a description of Pelagius’s arrival in Rome and the nature of the political accusations against him at the time. Pelagius wrote against the doctrine of original sin and Augustine responded in turn. The essay proceeds year by year to describe Pelagius’s location and his writings concerning various doctrines which frequently oppose those of Augustine. Pelagians are banished from Rome. The author lists the decisions of a number of councils on the subject of Pelagius’s doctrines followed by the Catholic Church’s opinion on original sin now. He includes scriptural evidence people use to support the notion of original sin as well as arguments against it. The author concludes that original sin is incapable of being proven.