Pelagianism and semi-Pelagianism are theological perspectives relating to the nature of man.  Pelagianism is a heresy, a false teaching.  It is the teaching by a fifth-century monk named Pelagius who taught that man’s nature was not affected by the fall of Adam and that all people are still free to equally choose between right and wrong.  When Adam sinned, his offspring did not inherit the sinful nature.  Pelagianism denies the doctrine of original sin and also denies that people are sinners by nature (Ephesians 2:3).  It states that people become guilty of sin only when they choose to sin.  It was officially condemned by the church at the Council of Ephesus in A.D. 431.

Semi-Pelagianism is a modification of the Pelagianism heresy.  According to this position people are fallen, sinners by nature, that they are not free to equally choose God or not, but they are able to make the initial step towards believing in God.  Along with semi-Pelagianism is the doctrine of prevenient grace which says that God gives grace to a person, enabling the person to freely make a choice of God.  This doctrine was officially condemned by the Council of Orange in 529 A.D.