Pelagianism was a 5th-century heresy taught by Pelagius and his followers which stressed that humans have the ability to fulfill the commands of God apart from Sovereign grace, and which denies original sin. Pelagius' teachings were opposed by the Church and it's leading figure (Augustine) in particular. Simi Pelagianism: Later, John Cassian's doctrine in a compromise between the Pelagius view and the Augustine view surfaced. This doctrine taught man was not dead in tresspass and sin, just sick. That man was only weakened by the fall and that man had the ability to save himself by accepting or rejecting of his own will, Christ's offer. Pelagius himself was excommunicated, and his theology condemned by a series of church councils, though the issues of the doctrine of free will have remained a sore point for the Church even to our day. The Church looks on the three positions as, St. Augustine regarding natural man as dead, Pelagius regarding him as alive and well, and Cassian regarding him as being merely sick. Augustine's position being the only one that leans entirely on the Sovereign mercies of God. [ back
In Christian theology, the doctrine that sinful humans can achieve reconciliation with God initiated by their own beliefs, actions, and/or works.