In his dispute with the Pelagian heresy, Augustine modified the early theory of freedom of the will. The basic position of the Pelagians is to adhere to the theory of good nature, deny the theory of original sin, and believe that whether a person is saved depends on his own choice. As long as people act in accordance with their inherent good nature, they can choose the good and be saved, without the grace of God. . Augustine realized that his early views might be exploited by the Pelagians. He said in the Corrigendum that the early writings were written to refute Manichaeism and mainly discussed the origin of evil. "These writings do not talk about God." of grace". Augustine emphasized in his anti-Pelagian writings that without the grace of God, human will cannot choose good. It can only be enslaved to sin, unable to follow the proper order, and loses the freedom of choice. The cause of ethical evil is not so much human freedom of will as human original sin. He developed the theory of "sin" in the Bible into the theory of "original sin". According to this teaching, the sins committed by Adam and Eve due to temptation were original sins inherited from generation to generation. Since then, human free will (1iberum) has been contaminated by sin, using free will to commit crimes, and completely losing God. When man was created, he was endowed with the ability of free choice (1iber-tas) to choose good and avoid evil. Only by relying on the grace of God can the human will be freed from the enslavement of original sin, make good choices, and regain true freedom. God's grace is first manifested in the atonement for mankind's sins. Jesus Christ, the Son of God, sacrificed himself in exchange for the new life of all mankind. From then on, the choice between good and evil faced by mankind was the choice of being a Christian or a pagan.